Operating systems are very concerned with how things are stored on drives. The typical computer system has a number of different drives attached. The hard drive, any floppy drives, cd-ROMs, or network drives might be be attached to your machine. You might think of each drive as a seperate tree. Disk drives usually have names. In the DOS/Windows world, drives have boring names like A: (The main floppy drive ) and C: (The main hard drive.) Newer operating systems allow more colorful names for drives like "my hard drive" or "Anita's floppy"
In GUI type environments like Windows and Macintosh System 7, the file and directory structure works in the same way it does in a command line operating system, but getting around to find what you want is much easier. Instead of typing a: at the C prompt to change to A: drive, you click the mouse on a PICTURE of the drive you want to move to. For example, in the File Manager program of Windows 3.1, to change the drive you click on a different drive box. The program then changes the focus to the drive you want with the directories and subdirectories showing on the left side of the screen and the files showing on the right. Not only is this system more user-friendly, but you can see more of the directories and files you have at the same time. Some operating systems and file management programs limit you to looking at a small part of the directories, subdirectories, and files residing on your computer. For example, if you are in the WINDOWS directory, you can look at all the subdirectories and files DIRECTLY under this directory, but you can't look at the files in the WORD subdirectory unless you change to that subdirectory. Also, once you change to that subdirectory, you can see all the files and subdirectories under the WORD subdirectory, but you can no longer see anything else directory under WINDOWS. If you are sitting on the branch of a tree and can see all the leaves and branches leaving from your particular branch, but you can't see the rest of the tree.