\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.

\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!)  

\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.

\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.  


\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}