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\me{Andy Harris, aharris@klingon.cs.iupui.edu}  % author(s) names and/or email address
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\docheader{Introduction to Computing}
{8}   % module number
{Communication and Internet Protocols}

\begin{goallist}
\item  Students will recognize the main protocols used in Internet
       communications
\item  Students will send and receive email

\item Students will join a mailing list

\item Students will utilize newsgroups to find information

\item Students will identify levels of connectivity to the Internet

	% ...
\end{goallist}

\begin{prereqs}
\item Familiarity with the worldwide web and URLs  
\item Basic historical background of the Internet
\item 
	% ...
\end{prereqs}

% Page 2 ... 

\section{Structure of the Internet}  % Name of first section
Earlier in this course, we discussed the Internet.  We saw that the
Internet was a collection of protocols, hardware, and software
components that enabled people to communicate via computers all over
the world.  We explored the world wide web, which is a major part of
the Internet, and learned how it might be used to find all kinds of
information.  

As exciting as the web is, it is only a piece of an even larger and more
significant entity.  The Internet is made of other components that
have other uses and characteristics.  

Our purpose in this unit is to discuss the Internet in more detail
than we have done before, and to learn some new ways we can use these
additional Internet tools.  

  \subsection{Protocols}
The Internet, as you remember, is a combination of hardware and
software.  Another very critical component of the Internet is the
protocols, which are a series of agreements about how information will
be shared and communicated between machines and networks.  The
protocols allow computers with different architectures and
operating systems to share information. 

It is important to note that protocols are NOT the same as programs.
A protocol is simply an agreement about how data will be structured
and communicated.  Internet programs are designed to take advantage of
one or more of the protocols.

    \subsubsection{TCPIP}

TCPIP (Transfer Control Protocol / Internet Protocol) is the
underlying protocol of the Internet today.  It is the protocol that
helps to split messages up, helps them find their way to the
correct destination, then causes them rejoin at the destination.
TCPIP is very important, but you rarely interact with it directly.
All the other protocols take advantage of it.  

TCPIP has been with us since the earliest days of the ARPANet.  It is
showing some signs of age, since it is being used for purposes its
designers never imagined!   Some other approaches to underlying
Internet protocols are being studied.  One notable possibility is a
concept called ATM  (Nope, not Automatic Teller Machines, but
Asynchronous Transfer Mode.)   

    \subsubsection{Telnet}

One of the earliest protocols to be used regularly is called telnet.
The telnet protocol allows a user to access a remote computer. If you
have the permission of the owner, you can use your computer as a
terminal of another computer.  If Terrence has an account on a big
unix machine at work, and that computer and his home computer are both
attached to the Internet, he can use telnet to have his computer 'call
up' the unix machine at work.  Once he does this, his computer is
acting simply as a terminal.  The screen he sees is being sent by the
remote computer, and anything he types will be sent there.  His own
CPU is doing very little work.  Any instructions he sends will go to
the remote computer.  

Why would anyone want to do this?

Telnet allows people to work on computers regardless of geographical
limitations.  It allows people to set up complex programs on
mainframes or other computers, and let people log in to this
computer.  One good example is the library of Congress Information
System (LOCIS).  The Library of congress maintains a huge database.
Through telnet connections, people can access the LOCIS computer from
anywhere in the world.  

Telnet is a very inexpensive protocol to implement and utilize.  It
does have disadvantages, however.  The remote computer does all the
work.  It doesn't matter how nice the graphics capabilities are on
your local computer, for example, because you will be forced to use
plain text most of the time when working on a telnet connection.
Also, not all computers on the Internet allow unlimited telnet access.
(In fact, very few do.)  It is far more likely that a computer will
allow you access only if you already have an account on that machine.
In other words, you must have previously arranged permission from the
owner of the remote computer in order to use that computer.  Telnet is
still used extensively by computing professionals, and it is often
used by large institutions such as libraries, universities, and
government institutions as a very inexpensive way to provide access to
information on mainframes.  The Indiana University system, for
example, uses a system called IUIS (IU Information System) for student
scheduling and other purposes.  If you have registered for class by
computer at an IU campus, you probably used IUIS via telnet (!)

There are special programs designed specifically to help you use
Telnet.  These programs are generally referred to as terminal programs
or telnet clients.

    \subsubsection{FTP}

FTP stands for File Transfer Protocol.  This protocol is a special
protocol which is designed to facilitate copying information between
computers through the Internet.  Whenever you download a file from the
Internet, you are probably using a form of the FTP protocol.  Much of
the time, FTP happens automatically through Web browsers, but there
are special FTP programs as well.  These FTP clients look like file
management programs (with the directory tree structure and all!)
except they also allow you to connect to a remote computer as well,
and look at the file structure of that computer.  Of course the
purpose of this is so you can copy and move files between computers.
An FTP program often looks like a file management program with TWO
directory structures.  You might use such a program if you have access
to two Internet computers, and you want to back up some of your files
on the other computer.  The information you are reading now was
created on a unix computer through Telnet, then FTPd to a couple of
other computers for review! 


    \subsubsection{Mail and News Protocols}

If the web is the most glamorous protocol, the mail / news protocols
are the work horses of the Internet.  These protocols are designed
simply to transfer text from computer to computer.  There are a number
of related protocols, including MNP, SMNP, POP, and on and on...  It
really isn't that critical to understand the difference between them.
The important thing to understand is that when you are reading mail or
news, whatever program you use to do this is using a mail/news
protocol.


    \subsubsection{HTTP}

HTTP stands for hypertext transfer protocol.  This is the protocol you
already know and love.  The WWW is based on this protocol.  HTTP has
some interesting characteristics.  It was designed to make the
Internet easier to use, and it accomplishes this in two major ways.

First, the HTTP protocol integrates many of the other protocols, so if
you have a program that can understand HTTP, it knows how to handle
other protocols such as gopher or ftp.  Some browsers can also handle
mail, news, and telnet.  

Secondly, HTTP is designed with HYPERTEXT in mind.  The earlier
protocols often were implemented on text - only displays, and had
command line - style interfaces.  This was not a problem when the
Internet (and its precursers) was populated by research scientists and
the like who actually seemed to ENJOY the confusing unnatural
interface.

(Really.  They dig that kind of stuff.)

HTTP encourages hypertext multimedia.  Hypertext, as you remember, is
text with links built in.  These links can be activated to allow the
user to go to a related topic.  Multimedia refers to the ability to
incorporate text, graphics, sound, and other media in the same
document.  Modern users are used to both concepts, and almost expect
to find them in programs.  The HTTP protocol is thus the most
friendly.  It is relatively easy through HTTP to share documents that
contain all kinds of information.

\begin{quest}
Why do many URLs begin with the term http://?
\ans
Because URLs are addresses or paths.  They begin with the protocol
name.  The most common protocol you will activate is an HTTP document.
Thus, most of the addresses on the worldwide web begin with http://
Occasionally you will find an address that begins with another protocol
such as ftp:// or telnet://.  As you might have guessed, these are
references to documents encoded for use with those particular
protocols.
\end{quest}

    \subsubsection{other protocols}
 
There are a number of other protocols that are used on the Internet.
Many of them are used mainly by computer professionals for maintaining
and testing connections (such as ping, which checks to see if a
certain site is running).  Others (such as gopher) were very popular
once, but now have been supplanted by another protocol.  The worldwide
web has made a number of smaller protocols far less important to the
average user, because you don't really have to know which protocol is
being used.  


 \subsection{The DNS system}

All these computers that are connected to each other via the Internet
need some way to 'find' each other.  There is a large system somewhat
like a postal system that assigns each computer a special address.
    
    \subsubsection{IP numbers}

The addresses are called IP numbers.  An IP number has four 'digits',
with each digit represented by a number from 0 to 255.  The smallest
IP number is 0.0.0.0 The largest one is 255.255.255.255 The computer
that this document was written on has an IP number of 134.68.140.61
These numbers are used very much like a zip code to help a packet of
information find its way to the proper destination.

    \subsubsection{Domain Names}

Numbers are, of course, easy for the computer to deal with, but
confusing for human users.  Computer scientists developed a system
called the Domain Name Server (DNS) system.  It was devised to give
verbal equivalents to IP numbers.  Many computers have domain names in
addition to IP addresses.  The Domain names are paired with the IP
numbers in a large database that is distributed throughout the
Internet.  So far, you may not have used any IP numbers.  Most of the
computers you access through a web browser have a domain name.  You
will only need to know about IP numbers when you encounter a computer
which does not have a name assigned.

The DNS system is organized in a tree - like structure based loosely
on the organization of the ARPANet.  All the computers in the Internet
are thought of as belonging to a specific wide domain.  Each domain
might have a number of subdomains, which might have a number of
computers in it.  Finally, each computer may have a number of users
who own or regularly use the computer.  

Part of the DNS tree structure is shown here:

%insert graphic of DNS

There are two main ways of organizing the highest level domains.  The
ARPANet defined domains with three character abbreviations based on
the type of organization which owns the computers.  The most common of
these names is summarized in the table below:

\begin{tabular}{|l|l|} \hline
Domain  & Type of Organization \\ \hline
.edu    & Educational institution \\ \hline
.com    & Commercial or business \\ \hline
.gov    & Government organization \\ \hline
.org    & Non-profit organization \\ \hline
\end{tabular}

You might also find two character domain abbreviations, like .fr or
.au.  These are international domains, which represent the country of
the computer.  .fr stands for France, and .au stands for Australia.

    \subsubsection{Subdomains}

Each domain is broken down into a series of subdomains. Subdomains are
generally large organizations.  In the .edu domain, for example,
indiana is a subdomain representing Indiana University, and iupui is
another subdomain representing IUPUI. 

\begin{quest}
Why do we have indiana and iupui in lowercase letters?
\ans
One of the most common operating systems on the Internet is called
Unix.  Unix is case - sensitive, meaning that INDIANA is not the same
as indiana.  To avoid confusion, most domain names are almost entirely
made up of lower case letters.  (even if they are not on unix - based
computers!)  
\end{quest}

Within a subdomain, individual computers are also frequently given
names.  In one computer lab, all the computers are given names of
ships or planets from a popular science fiction series.  

A computer might have the following complete DNS address:
klingon.cs.iupui.edu

From right to left, we can interpret the address in this way:

edu = educational institution
This computer belongs to some type of school or other educational
institution.

iupui = Indiana University / Purdue University / Indiana
This is the name of a particular university.  If we did not recognize
IUPUI as a university name, we might be stuck here.  It would still be
reasonable to assume that IUPUI was the name of a school, though,
because of the .edu extension.

cs = Computer Science
Again, we might have to just guess that cs means computer science.
Organizations might abbreviate departments as part of the internal
naming structure they choose.  CS is a very common abbreviation in 
universities for computer science.

klingon = the name of the particular computer.  
The only reason we know this is because it is at the very left hand
part of the complete name.  

As you can see, there is a lot of guesswork involved in interpreting a
domain name, but the letters are not random.  There is usually some
kind of organization to the name.

Organizations apply to InterNIC for a particular subdomain name.  Once
they receive that name, they can create subdomains however they want.

To make things a little easier, many subdomain owners have followed a
special convention:  Since most transactions are done via the
worldwide web, a special subdomain is often designated specifically to
hold the main documents that organization wants distributed via the
web.  That subdomain is usually something like:
www.orgname.com
where orgname is the name of the organization (or some other catchy
word) and .com is replaced by whichever domain type is appropriate.

\begin{quest}
What might be the domain names for the following organizations?
\begin{itemize}
\item The White House
\item Microsoft
\item National Public Radio
\item Indiana University Computer Science Department
\end{itemize}
\ans
\begin{itemize}
\item The White House : www.whitehouse.gov
\item Microsoft : www.microsoft.com
\item National Public Radio : www.npr.org
\item Indiana University Computer Science : www.cs.indiana.edu
\end{itemize}

Note all lower case, no spaces, and abbreviations.
\end{quest}

    \subsubsection{Userids}
    
In the Internet world, you see that computers have names.  Individual
users also have names.  The names are usually given to users when they
are given account on a Internet connected computer.  Most local area
networks require each user to have a name.  Most mainframe computers
have a similar requirement The user's name is often called a login or
userid.  Frequently these names are based on the user's actual name,
but it is often abbreviated and put only in all lower case letters.  A
user named "Georgia W. Wilson" might be assigned userids like gwilson
or gwwilson.  The advantage of this is that if we can combine the
userid with the domain name of her system to get a complete address.
If Georgia had an account on the klingon computer described above, her
complete Internet address would be "gwwilson@klingon.cs.iupui.edu".
Other Internet users anywhere in the world could send messages to her
by using that address.

    \subsubsection{Passwords}
Security is an important consideration in the Internet world.  The
computer has know way of knowing who you are.  Most LANs or mainframes
require each user to log in, or sign on to the system.  To do this,
you type in your userid at a prompt.  You are then prompted for a
password.

passwords are special codes you use to 'lock' your account.  Obviously
you need to be careful about protecting your password if you are
building nuclear power plants or something, but what about the rest of
us?

A student recently got some help from her friend on email.  She gave
him her password to a class account, and he wrote it down.  Apparently
some of his buddies found the password and logged in using the
student's userid and password, and sent a very obscene message to the
class.  The student nearly lost her account, because she had been
sloppy with her password.

Change your password regularly!  

Some hints:

\begin{itemize}
\item Don't use your dog's name.  People will guess it
\item Don't use words in English, people can hook up spell checkers
\item Consider combining words and numbers
\end{itemize}


  \subsection{How it all works}

This large collection of computers all over the world is much too
large an entity to understand without some type of organization. As
you have seen, computer scientists like to take large entities and
break them into tree - like structures that are easier to comprehend
and deal with.  The Internet is put together in exactly the same way.
We will start by thinking about the smallest units, and see how they
are attached to form the entire Internet.

    \subsubsection{The local computers and the LAN}

The smallest unit on the Internet is the individual user.  In many
offices and homes, each person has her own personal computer.  In
other organizations, there may be a very large computer that each
member of the organization has an individual account on.  In any case,
it is important to imagine that each individual has a userid within
the local organization, and that all the computers within this
organization are tied together with some sort of local area network.
Often each department or floor in an organization has a LAN.  LANs
usually consist of up to 100 computers attached together through wires
and special software so they can communicate easily.  Often, LANs are
tied together within a large organization to make WANs, or Wide Area
Networks.  For our discussion, we will consider LANs and WANs to be
pretty much the same thing.

    \subsubsection{Lans and Routers}

The LAN makes communication between members of the same organization
much easier, but The Internet is a MUCH larger unit, and LANs need
some help in order to make an Internet connection possible.  LANs are
attached to special computers called routers.  A router is designed
with one job in mind; directing traffic between the LAN and the rest
of the Internet.  In essence, when you send a message anywhere outside
your LAN, you send it to the router, which takes care of distributing
the message to the rest of the Internet.  Likewise, any messages or
documents you get from anywhere on the Internet have gotten to your
machine through your router, and your LAN.

    \subsubsection{Routers and The Internet Backbone}

The router takes the information you give it, and uses TCP/IP to send
the packet to other routers.  Eventually, the packet will get to a
high - speed communication system called the Internet Backbone.  The
'Information Super-highway' we keep hearing about is really a reference
to the high-speed connections between a number of National Science
Foundation sites.  In the Indiana area, most packets make their way to
the Internet backbone through the University of Illinois site.  From
here, packets are transferred to other routers via the IP addresses,
until the packets eventually find the correct destination.  All this
often happens in seconds.  The next time you get frustrated about how
long it takes to view a web page, reflect on the process it took to
get to your computer!


    \subsubsection{The Client - Server Approach}

Often in Internet computing, you will encounter the terms "client" and
"server."  The Internet uses what is called a client / server model of
communication.  This is how it works:

Tim goes into a drive - through restaurant.  He sees a big menu full
of choices.  He chooses a "big fun cool wacky meal," and informs the
little speaker of his decision.  He hears a tinny little voice confirm
his request, then tell him how much it will cost, then tell him with a
slightly bored expression to drive up to the first window.  Presumably
as he drives around the restaurant, some kind of food preparation is
happening inside.  He gets to the window and exchanges his cash for
the food, then drives off.

In this illustration, Tim is the Client.  He makes requests and gets
stuff back.  the restaurant is the server.  It sits around waiting for
requests from clients, processes them, and gives the results to the
clients.

Most of the software that is designed to be used via the Internet is
classified as client software or server software.  Client software is
designed to be used by ordinary users.  Web browsers, email programs,
ftp programs, and most of the other Internet programs you will
interact with as a user are clients.  The servers are the big Internet
computers and programs which are set up to interact with clients.
They generally have information designed to be read by various
clients.  For example, the web browser program you interacted with
earlier was a web client (to be more precise, an HTTP client.)  Let's
say you used this program to go to the WhiteHouse at
http://www.whitehouse.gov.  When you place the url in the little box
and tell the browser to go there, it tries to find a server at that
address.  The white house has a computer (sadly, it might not really
be in the White house, but let's just pretend it is!!) with all the
pages of the white house web site, and the appropriate programs to
communicate those pages to your browser.  The white house is acting as
a server.  (I guess that is somehow appropriate!)

\section{Levels of Connectivity}

One area that frequently confuses people about the Internet is the
fact that it is possible to Interact with the Internet on many
different levels.  Each of these different levels of connectivity
implies different compromises between speed, expense, and
capability.  The connection we are concerned with here is the
personal computer or LAN to the router.  there are also differing ways
of connecting the router to the Internet beyond, but that is beyond
the scope of this course.

  \subsection{Direct connection}

The most powerful type of connection is a direct connection.  A
computer with a direct connection is always attached to the router,
usually with some type of high-speed phone line or fiber - optic
cable.  A direct connection is VERY expensive, but it is powerful and
fast.  Most computers that work as servers have some kind of direct
connection, but such a connection is often too expensive for a typical
user who is not interested in SERVING information as much as being a
CLIENT.

  \subsection{Dial - in connection}

There are a number of compromises we can make so that a computer that
does not have a direct connection can still have some type of
relationship with the Internet.  Many companies and most universities
have one or more mainframes or other large computers with direct
connections to the Internet. Members of that organization are give
accounts on those huge machines, with a small amount of hard drive
space dedicated to that individual.  These large computers are also
frequently attached to a bank of modems.  People with modem - equipped
computers at home and accounts on these large computers can use
special software to have their home computer call the larger machine.
Once the communication is established, the home computer becomes a
terminal to the large one.  Note that this is functionally very
similar to telnet.  The only difference is in the type of connection.
Telnet is between two computers which BOTH have IP numbers and
connections to the Internet.  In a dial - in connection, only the
large computer has an IP number, and the home computer does not exist
as far as the Internet is concerned.  All transactions happen in the
CPU and drive space of the LARGE computer.  The home computer is
nothing more than a terminal.  If you used such a connection to
download a specific piece of software, for example, that software
would be stored in your drive space on the LARGE computer.  You would
need to use other strategies to copy it from that large computer to
your computer at home.  Obviously, this is a bit of a disadvantage.
Another disadvantage of this type of connection is that a dial in
connection usually implies only command - line interfaces, which are a
bit ugly and difficult to work with.  No matter how nice the graphics
and sound capabilities of your home computer might be, they are tied to
your own CPU and will not be utilized when you are using a dial - in
style connection.  Still, dial in connections are very popular because
they are extremely inexpensive to maintain, provide the most important
Internet services, and work with even very limited home computers.
Most universities give all students at least limited dial - in
service.

  \subsection{Slip - PPP connection}

Another approach is becoming more popular, because it offers many of
the benefits of direct connection, but can still be done at a home
without a permanent dedicated Internet phone line.  This approach is
called PPP (Point to Point Protocol).  A related protocol is called
SLIP (Serial Line Interface Protocol).  PPP is replacing SLIP.  For
our purposes, we will consider them the same thing.  An organization
with PPP capability may be set up the same way as the dial in service
model.  There is a large computer with a permanent direct connection,
and a number of people with smaller home computers that want to
connect to the larger machine through cables or phone lines.  When
these machines are connected via PPP, the larger machine has its own
IP number, and a bank of temporary IP numbers it is allowed to "check
out," like library books.  Your home computer must have a special
program that knows how to hook up to the large computer and "check
out" an IP number.  You activate this software, and it makes the
connection to the large computer through your modem.  As long as this
connection is open, your computer has its own albeit temporary IP
number.  In effect, you have 'faked out' the Internet into believing
you have a direct connection.

With a PPP connection, it is really your computer at home with the
Internet connection.  You can run programs that take advantages of
your graphics and sound capabilities (like most web browser
programs), and anything that you save will be saved to your own
computer, not the large one.  When you break off the connection, the
IP number you borrowed will be returned to the pool.  The next time
you utilize this service, you may get a different number.

This approach is not terribly expensive to maintain, and it allows
people to take advantages of their own computer's capabilities.  The
user has to set up the PPP program as well as setting up and
installing any client software he wants to use.  This can be
intimidating, but it gives the user a great deal of power.

A PPP connection is not appropriate for server programs or
information.  For example, if you wanted to make a web page and make
it available to everyone on the Internet, you couldn't do it with a
PPP account alone.

\begin{quest}
Why?
\ans

The problem is that you would not have a consistent address!  A PPP
account gives your computer temporary access to the Internet, but if
you stored a web page on your computer, people couldn't reach it when
you are not attached!  Also, your IP number would be constantly
changing!

The common way around this problem is this: When you are given a PPP
account, you frequently are given a dial - in account as well.  All
your email goes to that account, and if you want to have a web page,
you put it in that account as well.  Then you can either use dial - in
connections to modify that dial - in account, or use PPP and a telnet
client to attach to that account and modify it.  

\end{quest}



  \subsection{Commercial Service providers}

The most popular way for people to get started on the Internet and
related issues is through commercial service providers.  If shirts
with little alligators were the icon of the '80s, floppy disks in the
mailbox promising 10 free hours of Internet access may well be the
icon of the 90s.  The number and type of such providers has changed
dramatically in the last few years, and it is easy to be confused
about them.

    \subsubsection{Proprietary Networks}

Before the Internet became popular with the general public (Waaaaaay
back in....say, 1990!) there were a number of privately owned
corporations which provided services much like the Internet.  The most
prominent of these are Compuserve, Prodigy, and America Online,
although there are many others.  These 'private networks' have some
significant differences from the Internet at large.  They are
generally placed on one large computer or network with many many modem
ports.  The information on the system is privately owned or
contracted.  Such systems might have extra controls that the Internet
does not have, such as 'censoring software' that automatically rejects
any messages which contain objectionable words or phrases.  (who
decides what is objectionable?)  The materials on such networks can be
much more clearly defined and organized, because they are not created
as randomly as the Internet at large.  Originally, each of these
services was an independent 'information island.'  If you belonged to
one service and your sister to another, you were pretty much out of
luck.  These days, the proprietary networks all have some kind of link
to the Internet, and allow you to exchange email and web pages with
anyone in the world who has any kind of Internet access.  The down
side is the cost.  Once your free hours are over, you pay the service
by the hour.  There are many stories of people racking up horrible
on-line bills by losing track of the time.  This is especially
troublesome if you spend all this time using the service provider as a
gateway to the Internet, because the Internet stuff cost the provider
almost nothing!  If what you really want is Internet access, and you
will want to be online more than a few hours a month, these providers
may not be the most cost - effective technique for you.

    \subsubsection{Internet Service Providers}

Internet Service Providers (ISPs) are a new class of business that
suddenly came into being within the last few years.  These providers
are simply folks who own large computers with direct connections and
hard drive space for rent.  When you sign up with one of these
providers, you can get varying levels of service.  Most people get
some kind of PPP access and drive space for email and other permanent
document storage.  In this way, you always have an Internet presence
online, for a relatively small amount of money.  Many of the ISPs
offer programming services and business accounts, so you can get a web
page for your small business, for example.  The ISP approach is
probably the best bet if you plan to be connected to the Internet for
more than a few hours a month, and want to experiment with other
Internet ideas such as building homepages and doing business online.

The problem with ISPs is that the business is so new that there are
very few controls.  Check around with any of the computer types you
know to see which are the most trustworthy ISPs in your area.  This
field is bound to change as telephone companies and other large
corporations get into the fray.


\section{Email}

Email, which stands for electronic mail, is a tool used to send text
messages between computers and users on the Internet.  The key to
email is the email address.  Each person with an Internet account has
such an address.  As we have discussed, this address is usually a
combination of the userid and the domain name of the computer or
system that user's account is on.  For example,
president@whitehouse.gov is the email address of the US president, and
the VP is vicepresident@whitehouse.gov.  Georgia Wilson (remember her
from earlier in this chapter?) has an address of :
gwwilson@klingon.cs.iupui.edu.

Email uses the mail /news protocol.  You would generally have a client
program to help you with email.  These programs are referred to as
mail readers or email clients.

  \subsection{The problems you can solve with Email}

Email is a communication tool, so the problems Email are best at are
communications problems.  Email is very inexpensive, and relatively
quick.  It is just as easy to send an email message across the world
as it is to the office next door.  Any time you want to communicate
with another person who has an email account, it is an alternative.
Just as a fax number has become a requisite part of a business card,
an email address is becoming a critical part of being connected in
business.  The course you are taking now was developed by a team from
eight different campuses.  Most of our communication was via email.
Such cooperation was one of the earliest goals of the Internet.  Email
helps to break down geographic barriers.

  \subsection{Tools common to Email programs}

There are many email readers available.  The particular program you
use may vary based on what type of connection to the Internet you
have, what kind of computer you are using, and what specific needs you
may have.  Regardless of this diversity, there are certain tools you
can expect to find in nearly any email client.

    \subsubsection{Customized Text Editor}

The heart and soul of email is writing messages, so it is not
surprising that you would have some kind of editor built into an email
program.  Generally, email programs include text editors that are
simpler than most word processors.  this is really not much of a
problem, because email sends essentially ASCII text, which is what
text editors are best at.  There are email programs with a spell -
checker built into the program.  This is an especially handy feature,
because it is very embarrassing to send an email to someone with
misspellings in it.  Many email programs also give you the option to
use some other text editor you really like and import the document
into the email program for mailing.

    \subsubsection{Send Command} 

Once the message is done, you obviously need some kind of command for
sending the message to its destination.  Somewhere on the document,
you will be given a place to put the email address of the recipient.
Be very careful when typing in this address!  If you make a mistake or
misspell the email address, your mail will not go through.  The post
office can guess when your address is a little sloppy, but the DNS
system cannot!  Check carefully before sending your message.  Once it
is sent, you cannot get it back!  Be especially aware of this if you
are sending an angry message you may regret later.  Once you activate
the send command, your letter will be broken into TCP/IP packets and
sent to the recipient, where she will use her email program to read
it.


    \subsubsection{Address Book}

Email addresses can be obscure and difficult to remember.  Most email
programs have some sort of address book that allows you to store the
addresses you frequently mail to under a nick name.  Rather than
having to remember your mother's address as dxdg05a@prodigy.com, for
example, you could store her address in the address book and give her
a nickname like 'mom'.  When you are ready to send your mom a message,
you can just type mom in the recipient spot, and the program will
replace that with her actual address.  Much of the time, you can also
use such features to group a number of addresses under one name.  If
for example, you were a manager and wanted to frequently send messages
to all members of your department, you could store all such names with
a nickname of 'department.'  When you send a message to 'department'
everyone in the list gets the message automatically.

    \subsubsection{Storage area for incoming mail}

After you send all this mail, you will probably be getting mail from
others as well.  One of the jobs of the mail program is to keep track
of the mail you receive when you are not online.  When you start up
the mail program, it should tell you about any mail you have received
since the last time you checked.

    \subsubsection{Mail reader}

Email programs will have some way of allowing you to read any of the
mail you have gotten.  It will look a lot like the editor you use to
send mail, but you cannot usually write in a message you are
receiving.  There are usually a number of commands built into such a
system which allow you some special flexibility: 

\begin{definition}
\item [\bf reply]

Allows you to reply to the person who sent you that message.  Usually
asks you if you want to include the message you are replying to.  It
will then send you to the editor part of the program, automatically
addressed to the person who sent you the mail you were reading.  If
you chose to include original message, you will see that message in
the editor as well.  This is especially handy if somebody asked you a
number of questions in an email and you want to respond to them
individually.  You can edit a copy of their message and put the
appropriate response after each question.

\item [\bf forward]

Allows you to send a message on to another person.  If you received an
email which somebody else should see, you can use a forward command to
copy the mail to the new person.  There are 'chain emails' which have
been forwarded thousands of times across the Internet.  They are just
as annoying as the paper kind, but easier to delete.

\item [\bf save]

Lets you save the message permanently.  This is very useful when the
document contains information you will need later.  The document is
saved as a plain text file you can manipulate with a text editor.

\item [\bf delete]

This command is very important.  Once you become active with email,
you will receive many messages.  It is important to do a little
housekeeping now and then so the number of messages in your account
does not become completely out of hand.

\end{definition}

  \subsection{Email etiquette}

As with any form of communication, there are certain rules of behavior
which should be considered when using email.

Email is written communication, but it does not have the formality of
earlier written forms.  It has a much more immediate, less formal feel
than paper, pen, and stamp mail.  Email is also essentially one - way
communication.  There is no immediate feedback and interaction.  Also,
written communication by definition allows far fewer context clues to
its meaning as face - to -face and telephone conversation.  Any
written communication must be carefully considered so that it is not
misunderstood, but email lends itself to casual interaction.  The
potential for real misunderstanding is clear.

When you compose an email message, pause and read over it again before
you send it.  Once it is sent, you can't get it back.  Remember that
your grammar, spelling, and vocabulary send a message as clear as the
words.  If your writing is sloppy, your message may not get through to
your recipient.

Be very careful about using humor in email.  Without the context cues
of other forms of communication, humor can very easily be
misconstrued.  Often something you think is funny will insult the
recipient.  One student thought he was entertaining his classmates by
sending a series of jokes over email.  The jokes became gradually more
vulgar, until a classmate was finally insulted, and the jokester
nearly had his email privileges revoked.  If in doubt, save the humor
for less risky types of communication.

Email is not a secure form of communication.  By nature, the Internet
is not a very private place.  Messages float all over the place.  It
is hard to know who will see your messages, and where they may be
forwarded.  It would be very poor judgment to use your office email
account to send a message to your friend complaining about what a fink
your boss is.

DO NOT USE ALL CAPITAL LETTERS!!!  By convention, capital letters in
an email message are considered shouting.  If you write all in caps by
habit, all the people you email will think you are shouting at them.
It is considered a bit rude.

Consider using emotion symbols.  In order to make email (especially
jokes) more readable without requiring people to become master
writers, some special conventions have appeared.  Often, people will
interject little parenthetic comments in their writing to help you
understand the meaning.  The following example will illustrate the
principle.

The boss is a PIG.

The boss is a (wink) PIG (grin!).  

Obviously, the second sentence was meant in fun.  It is not so obvious
that the first one was intended to be humorous.  Of course, the boss
may not find either one particularly funny.

Another way people try to interject little emotion hints in email
messages is through smileys (sometimes called emoticons).  These are
special combinations of ASCII symbols that are supposed to convey
emotion.  :-) stands for happy.  :-( is sad.  Don't worry, you won't
have to memorize them.  Turn the page sideways and you will understand
how they work.  Of course smileys get far more complex.  People have
made entire dictionaries of smiley symbols.  Some of my personal
favorites ;-P (winking and sticking out tongue), %-| (my glasses are
broken), <<<<< :- o--- (Marge Simpson eating a lollipop).

There is a school of thought that says smileys are shortcuts, and no
substitute for carefully composed writing.  The best guideline is to
remember who you are writing to, and what your message is supposed to
be.  this will help you decide if smileys are appropriate.

Email users have also developed a number of abbreviations that are
used to shorten common sayings.

\begin{quest}
How many of these can you guess?
\begin{itemize}
\item imho
\item fyi
\item btw
\item rotfl
\item rtfm
\item cul8r
\end{itemize}
\ans
\begin{itemize}
\item imho = in my humble opinion
\item fyi = for your information
\item btw = by the way
\item rotfl = rolling on the floor laughing
\item rtfm = read the flipping manual (that's the PG-13 version.)
\item cul8r = see you later
\end{itemize}

\end{quest}


Remember that you are a person talking to another person.  Your reader
is not an account or a computer; neither are you.  Address your
messages to the person's real name, not just her userid.  Likewise,
sign your messages with your real name.


  \subsection{Disadvantages of Email}

As we have seen, one of the biggest disadvantages of email is the
capability for misunderstanding.  Email has some other disadvantages
as well.  It can be used to talk to more than one person at a time,
but the means for doing so can be a bit cumbersome.  At its core,
email is a one - to - one communication medium.  Email requires active
participation.  You have to check your email to get messages.  If you
do not check your email, you will never know that somebody has
contacted you.

  \subsection{Common Email Programs}

Which email program you use depends a lot on your type of connection,
type of computer, and personal preferences.  Here are a few of the
main ones:
\begin{itemize}
\item mail

This is kind of the mother of all mail programs.  It is built into
most unix systems.  Since unix is the foundation of many ISP systems,
it is the program you are almost guaranteed to have access to on a
unix account.  Mail uses a command line interface, so it is very
clumsy for beginners.  Still, it has a lot of power if you are willing
to learn how to use it.

\item pine Pine is another email program found largely on unix
systems, although it is also found on the PC.  Pine is easier to use
than mail, because it uses a limited system of menus.  pine is the
most popular mail program on ISP or university unix systems.

\item Eudora

Eudora is a program designed for use on PCs with direct or PPP
connections.  It takes advantages of the Windows GUI, so it has the
buttons, drop down menus, and other features you would expect in a
Windows program.  It also has features built in to grab messages from
a mainframe account if you are attached via a PPP account.

\item Netscape 

Netscape is a web browser, but the later versions also have a built in
mail program.  The mail program is similar to Eudora.  It takes
advantage of the GUI environment.  It is available for a number of
platforms.

There are of course many others.

\end{itemize}



\section{Talk and Chat}

Email is good for deliberate long - term conversations, but if both
parties are currently attached to the Internet, there must be a way
for them to connect a little more immediately.  There are a number of
protocols and programs designed exactly for that purpose. In general,
talk programs are those that are used between two people.  There is
another related class of programs which is designed to allow many
people (even hundreds) to communicate simultaneously.

New forms of these programs are coming along all the time, as
transmission speeds increase and technology improves.  Current chat
programs allow real - time sound transmission, drawing on remote
screens with a mouse, and even real - time video!

  \subsection{The problems they are good at solving}

If Heather is sitting at her computer, and wants to invite Chris to
lunch, she could send email to him, but he may not get the message in
time.  If she has a talk program, she can invoke it and tell it to
notify him she is calling.  If he is online, he will get a message
that Heather is trying to reach him.  If he chooses to make the
connection, they will both get a screen on which they can type
simultaneously.  They can interact directly and determine where they
will meet.

Chat programs illustrated their relevance during several recent world
emergencies.  Notably, during the war in Chechneya there were few
formal communication channels open.  There were, however, people
sending messages worldwide on chat lines.  Similar communication
occurred during the Russian coups attempt and other major crises.
Less dramatic uses of the technology have been used to have on-line
conversations about sporting events and political debates as they
occurred, and simply to waste long evenings.  There have been a number
of romances over chat groups, and at least one wedding which occurred
on a chat line.

  \subsection{The tools such programs usually give you}

Talk programs are a little bit less complex, so we will start with
them.  All they really need to have is a way of contacting the
recipient, a way of answering when you are called, and a way of
tracking the conversation as it is going on. Most talk programs divide
the screen in two windows.  One window represents the local machine,
the other window is the remote machine.  As you type, you see your
comments in the top window, and your recipient simultaneously sees that
message in his bottom window.

Chat programs are pretty much the same, except there may be many more
people on at the same times.  Usually you will connect to the name or
location of a group, rather than a specific individual. Once you are
connected to the group, you will see a screen with the conversation
scrolling along, and often you will have some way of determining who
else is taking part in the conversation.

  \subsection{Disadvantages of chat programs}

Unlike email, chat offers no record of the transaction.  If you say
something profound, it will not be automatically recorded.

Chat requires that both parties be using Internet connected computers
at the same time.

There are a number of distinct protocols being used for chatting and
talking.  If all interested parties are not using the same protocol,
they may not be able to connect.

  \subsection{Common Chat or Talk programs}

As usual, your selection of programs depends on the type of computer
and connection you are using.  Most of the relevant programs will
contain the term chat or talk in the title.  Some talk programs are
integrated into web pages, so you do not need a separate program.
Many of the web browsers have a real - time talk feature built in so
you don't have to get a separate program, but they often require that
both parties have exactly the same type of software installed.

\section{Mailing lists}

Mailing lists are special programs that help automate email
communication within a group.

  \subsection{Historical context of mailing lists}

When email became available, it was very popular, but people soon
found that it had some shortcomings.  Often, a group of people with
similar interests wanted to simplify the process of communicating via
email.  At first, if you had five people around the world who were
interested in your research topic, you would simply send the email
five times, once to each colleague.  This quickly became unwieldy if
you shared an interest with a larger group.  The solution was to use
the distribution list feature built into many email programs.  You
could learn the email addresses of all the people with similar
interests, and store them as one name in your address book.  This
worked fine as long as the list of people stayed relatively short, and
the people on the list didn't change too frequently.  This kind of
approach had some setbacks, though.  If a person no longer wanted on
the list, every other member of the list had to remove that person
from their own personal copy of the list.List management became a
messy job, so computer scientists developed a program that could
automate the mailing lists.

    \subsection{How mailing lists work}

The idea of these programs is very simple.  The program has an email
address, usually with the term listserv or majordomo in the name.
(Listserv and Majordomo are the two main types of programs used to do
mailing lists).  A person who wants to join the list could send a
command to the majordomo program through his email client asking to
sign on.  All members of the list is given another email address for
the actual list, which is also controlled by the majordomo program.
When a member sent a message to the list, the controlling program
would automatically send it to each member of the list.

  \subsection{Example: Fran and the Pygmy Hippos}

Fran has always had a lifelong fascination with pygmy hippos.  she
could talk about them for days.  Unfortunately, she has a very
difficult time finding people who will listen to her that long.  She
was beginning to feel she was the only pygmy hippo fan in the world.
Fran took a class that introduced her to the Internet and mailing
lists.  She knew this would be her chance to find other hippophiles
(yep, my spell-checker blew a gasket on that one!  I hit the ignore
button.).  She found a mailing list called hippos by searching around
the world wide web for mailing lists indexes.  The instructions told
her the hippo mailing list had two different addresses.  The first one
was majordomo@nml.zoo.org She knew by the majordomo part that this
address was the majordomo / listserv program, and that she would have
to send a message to it so she could be part of the list.  By
following the instructions she found on the index page, she knew she
had to start up her email program.  She did so, and composed a message
to majordomo@nml.zoo.org Her message contained only one line, which
again she got from the instructions.  It was: subscribe hippos She
sent the message, and in a few minutes she got back a response!  It
welcomed her to the mailing list, and told her she would start getting
mails soon from other members of the list.  It also told her how to
sign off of the list if she found it was not to her liking.  She
carefully saved this message, in case she ever needed it later.

Fran waited for a couple of days, and got some wonderful email about
pygmy hippos.  After watching for a few days, she wanted to send a
message to the group introducing herself and asking questions about
one particular family of hippos she knew about.

To send the mail, she went to her email program, and composed a
message to the list itself.  She knew the address, because it had been
in the instructions she saw on the web, and it was also in the first
message she got from the group.  She addressed her message to
hippo@nml.zoo.org.  She sent the message, and in a few days, got a
number of greetings and responses from fellow hippo lovers.  Fran
found newfound happiness and a group of fellow hippophiles (had to use
that word again!)  all over the world.

  \subsection{The problems you can solve with a Mailing List}

Mailing lists are ideal solutions for problems like Fran's.  They are
easy and inexpensive to set up and maintain, so you will see mailing
lists on just about any topic there is.  Many college courses now have
a dedicated mailing list, intended to encourage student interaction
and group - problem solving.  Mailing lists are also used inside
corporations so that groups within the organization can communicate
more easily through email.

  \subsection{The program and the list}

The most difficult aspect of working with mailing lists is the
distinction between the list itself and the program that controls the
list.  Both have email addresses, and both are usually on the same
machine, but they have very different purposes.  When you look at a
mailing list index (there are a number of them on the www.)  you will
see something like this.

THE HIPPO LIST
\begin{itemize}
\item To Join:  email:  majordomo@nml.zoo.org		
\item message body:  subscribe hippo
\item List address:  hippo@nml.zoo.org
\end{itemize}

The controlling program usually has a name like majordomo or listserv.
You will probably only send mail to this address twice, once to join
the list, and once to leave.  Any mail sent to this address is NOT
sent to a human, but to a program.  The program can only handle very
specific input, so you must type exactly what you are told, or the
program will reject your request.  If you say "Please subscribe me to
the hippo list" the program will not understand and will reject you.
Majordomo (or listserv) is a PROGRAM, not a PERSON.

The address you will use more often is hippo@nml.zoo.org.  This
address is the common address for the group.  It is also sent to the
majordomo program, but it is 'bounced' from there to the address of
every other member of the group.  Anything you send to the list
address will be read by human members of the group.  (and maybe
hippos, but they are pretty tough on keyboards)

  \subsection{Mailing List Etiquette}

This leads us to the major faux paus of mailing list members.  Once
you join a mailing list, you will undoubtably run across messages that
read: "Unsubscribe me" or something else similar.  The person who sent
the message has told you two things:

1)  They don't like the list anymore or the people on it

2) They don't know how to use mailing lists, because they sent a
command to the list, not the program.

If you are a mean-spirited person, you could send that errant soul a
scathing message decrying their ignorance and lack of manners.  Such a
message is called a "flame" in Internet parlance.  An exchange of
angry emails is called a "flame war."

Be very careful when using a mailing list that you track which
messages go to the controlling program and which ones go to the list.
You don't want people to flame you.

Mailing lists are related to email, so many of the same rules apply,
but there are a few new ones:

Any mailing list or other place that people gather together is bound
to have its own sociology.  As a group of people exchanges ideas,
there will be friendships, rivalries, in- jokes, and recurring themes.
Many mailing lists also develop their own codes and shorthand.  For
example, one mailing list that discusses flight simulators uses
abbreviations for all the major flight simulators.  FS5 stands for
Microsoft Flight Simulator version 5, WC3 is another flight simulator,
and so on.  This can be very intimidating if you are new to the group.
Different groups also have different expectations in terms of how much
they expect members to stay on the group topic, whether they allow
name - calling and other uncivil behavior, and the kinds of language
and discussions that are allowed.  If you do not follow the norms of
the group, you will certainly be flamed, and may be kicked out of the
group.

It is a very good idea to learn about the group before you get too
involved.  Just stay quiet and read without sending messages until you
get a feel for how the group interacts.  This behavior is called
'lurking' and is quite acceptable, even polite.  Once you feel you can
participate in the spirit of the group, feel free to do so.  If you
find you do not like the group, quietly unsubscribe through the
controlling program, and no one will know you were even there.

In general, try to stick to the topic the group is supposed to be
addressing.  If you have comments that fall outside the group's topic,
send private emails.

Once you develop some relationships within the group, carefully
consider what should be sent through private email, and what the
entire group should know.  For example, two students decided to cheat
on an exam, and discussed their plans over the class mailing list.
They neglected to notice that the teacher was also a member of the
group, and knew exactly what they were planning.  He sent the students
a private email explaining how mailing lists worked, and asked for an
extra homework assignment about security, ethics, and the Internet,
and there was a happy ending.  It might not have turned out that way.
Some information is best kept private.

  \subsection{Disadvantages of Mailing Lists}

Mailing lists can get out of hand quickly.  If you belong to a very
active list, or to many lists, you could easily pile up several
hundred messages in a day.  This becomes a lot of information to sift
through.

Mailing lists are very easy to create, but they are also easy to
destroy.  That really cool mailing list you saw last week may not
exist this week.  There is absolutely no central control of mailing
lists, so they come and go with amazing frequency.

It is impossible to know which mailing lists are available.  There is
no organizational scheme or structure to them.  It can be difficult
finding exactly the list you want.

  \subsection{Common Mailing List Programs}

As mentioned, the two most common mailing list server programs are
majordomo and listserv.  Mailing lists do not require special client
programs, because they use the email protocol, and exactly the same
programs you would use for email.

\section{Newsgroups}

Mailing lists are very good for certain kinds of communication, but
their lack of organization can be a serious drawback.  Early in the
history of the Internet, a more systematic system was developed called
usenet.  This system organized the major topics of conversation into a
number of large domains.  Each domain was then split into subdomains
and subsubdomains.  (There's that darn tree structure again!)  Some of
the main domains were

\begin{itemize}
\item alt:  alternative topics
\item comp:  computers and computing
\item sci:  science topics
\item rec:  recreation
\end{itemize}

The idea was a user could find exactly what topic she was looking for
by navigating the hierarchical structure.

The ideas were expanded when the Internet grew, but the basic
structure remains the same.

  \subsection{How newsgroups work}

Newsgroups are a lot like mailing lists, but the mechanics are a bit
different.  There are thousands of lists in the newsgroup system.
When your system administrator sets up your account, he subscribes to
a number of lists.  You can read and submit messages to any group that
your site is subscribed to.  Every so often, (usually late in the
night) all the newsgroups are exchanged and compiled.  If you send a
message to a newsgroup, the message will be stored on your system
computer until the next exchange occurs, then it will be distributed
to every other system in the world which subscribes to that particular
newsgroup.

Generally you need a special news reader program to read and write to
newsgroups, but most web browsers have this capability, so many people
read email through them.  Many email programs are also capable of
reading newsgroups, so they are commonly used as well.

  \subsection{The problems Newsgroups help you solve}
 
Newsgroups help you solve many of the same problems that mailing lists
are good for, but newsgroups have some additional advantages.
Newsgroups are generally a bit more structured, so they are likely to
be around longer.  They are also easier to find, and more likely to
have a moderator (person or program in charge, who keeps the group
civil and on - track) Newsgroups often have a FAQ document.  FAQ
stands for Frequently asked Questions.  In any newsgroup, there are
usually a number of questions that are asked all the time.  In order
to avoid answering the same questions all the time, experienced
members of the group post a FAQ with the most common questions and
answers.  If you ask a FAQ before reading the FAQ document, you are
likely to get flamed.

 \subsection{Newsgroup Etiquette}

The rules of behavior on Newsgroups are very similar to email and
mailing list etiquette.  In addition, be sure to read the FAQ before
asking obvious questions.  Lurking is a good idea!

  \subsection{Disadvantages of Newsgroups}

Newsgroups are not as quick as mailing lists or email.  It will almost
always take a day or two to get a response.

Just because you saw something in print on the Internet does not mean
it is true.  Anybody in the world can say anything they want on the
Internet, and they don't have to know what they are talking about.
Use judgment when reading messages, and consider how well you know
the source.

Newsgroups are home to many of the least savory parts of the Internet.
If you are concerned about your children's access to the Internet,
this is an area you should monitor.  The alt groups can be especially
troublesome, because there is very little control of the content that
goes there.  There is software you can buy which will password -
protect such groups so children cannot go there.

\section{Laboratory Assignment}  % comment out if not applicable

Find an appropriate email program.  Your instructor will show you
which ones are available on your system

Change your password.  Be careful that your password cannot be easily guessed.

Get the email addresses of five of your classmates.  Add them to the
address book of your email program.  Send them each an email

Subscribe to the class mailing list.  Your instructor will tell you
the controlling program address as well as the list address.

Use a newsgroup reader to find answers to the following questions:
Write down enough to prove you have found an answer.  You will email
it to the class list later.

\begin{itemize}
\item Find a joke

\item Tell about a rumor you found

\item Anything interesting for sale lately?

\end{itemize}

Send a short letter to the class mailing list.  In the subject area,
put your name and the section number of the class.  Write your answers
to the newsgroup questions in the message area of the test.  Your
instructor will grade the emails


\begin{vocab}   % vocabulary/main concepts list


\item [\bf Protocols]
A set of agreements about how information will be transferred among
Internet - connected computers

\item [\bf TCPIP] Transfer control protocol / Internet protocol
The underlying protocol of the internet.

\item [\bf Telnet] 
A protocol that allows one computer to be a terminal of another.  Both
computers must have active Internet conne ctions to use Telnet.

\item [\bf FTP] File Transfer Protocol
A protocol for sharing files between internet - connected computers.

\item [\bf HTTP] Hypertext transfer protocol
The protocol which makes the world wide web possible

\item [\bf DNS] Domain Name System (or Server)
The system of hierarchical organization that gives names to computers
and domains on the internet. 

\item [\bf IP Number] 
The number assigned to each computer on the Internet.  IP numbers are
used much like zip codes to help each packet find the right recipient.

\item [\bf Domain Names]
A system of names used to represent IP numbers.  Domain names are
easier to remember than IP numbers.

\item [\bf UserID]
The name each individual is given on his / her LAN or mainframe.

\item [\bf LAN] Local Area Network
A number of personal computers connected by cables and software.

\item [\bf Routers]
Specialized computers which handle TCPIP packets.  Routers hand off
the messages to other routers.

\item [\bf The Internet  Backbone]
A series of high-speed computers and cables designed to facillitate
Internet communication throughout the world. In the US, the NSF
backbone is the Internet backbone.

\item [\bf Client - Server approach]
A description of the way the Internet handles messages.

\item [\bf Client]
Software that is designed to ask for information from a server
program.  Most users use only client software.

\item [\bf Server]
Hardware or software that is set up to distribute information to
clients all over the world.

\item [\bf Direct connection]
A computer that has a direct line to a router.  Very expensive, but
gives great control. Generally only servers have direct connections.  

\item [\bf Dial - In Connection]
Uses a communication to make one computer act as a terminal of the
other.  The terminal computer does not exist as far as the internet is
concerned. 

\item [\bf SLIP - PPP] Serial Line Internet Protocol - Point to Point
Protocol.  Protocols which allow the server to 'loan out' temporary IP
numbers to clients.

\item [\bf ISP] Internet Service Providers
Usually small businesses that rent out space on computers with a
direct connection.  

\item [\bf Email Address]
The address used to find a particular person on the Internet.
Combines the userid with the domain name of their system with an @
sign.

\item [\bf Talk]
A protocol that allows two users to type simultaneously in real -
time.

\item [\bf Chat]
A program or protocol that allows many people to type simultaneously
in the same conversation.

\item [\bf Mailing Lists]
A protocol which uses programs such as majordomo or listserv to
automate email to multiple parties.

\item [\bf Newsgroups]
A protocol or program that allows users to exchange messages world
wide.  Newsgroups are a bit more formal than mailing lists.


		%  ...
\end{vocab}

\section{Summary}

The Internet has the potential to change society completely within the
next few years.  It is such an important new advance that we must
understand at least the basic structures and tools it provides.  In
this unit, we expanded upon the ideas we learned about the world wide
web, and investigated some of the other protocols that the Internet
provides.

We examined how the Internet is organized, how the DNS system works,
and how computers and individual users get names.  We also talked
about levels of connectivity to the Internet, and finally we looked
more carefully at email, mailing lists, and newsgroups.  

The Internet is no doubt a toolbox of major proportions.  If we
understand how it works and where it is going, we should be able to
learn the new tools it provides us with relative ease.  

Internet tools are about communication, and communication is central
to the human condition.  Perhaps some of the tools we learned about in
this section can be used to help people communicate with each other.


\end{document}

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Number of words: 8500