It's funny, but people seem to forget that every computer and every program installed on a computer comes with its own help file. Even the operating system of a computer has a help file and it really should be the first place to look for answers. Help files are designed not only to guide the usage of a computer, they're also designed to solve problems. au - This extension indicates a sound file. Most sound players will load up and play this kind of file. .art - This extension indicates an image file that was compressed with AOL (America Online) technology. Both Internet Explorer and the AOL service software can display this kind of file, however if you don't have AOL installed on your system, Internet Explorer will display it. If you're familiar with MS-DOS at all, you'll recall that it's a command-driven operating system that performs functions issued at the C:> prompt. The only way to get an MS-DOS computer to do something was to type a command at this prompt and if you can imagine, it was a rather cumbersome way to use a computer. As you can imagine, the cumbersome process of switching from floppy to floppy prompted the birth of the operating system. An operating system is a software program that controls how the computer's hardware (and installed software) works. It manages the activity of every component and then displays that activity as a user-friendly interface (GUI). If a single printer is available on only one computer in the network, every connected PC can send documents to it and print them out. Kids will enjoy the ability to play multi-player games and adults will enjoy the ability to blast a single message to everyone at once or maintain a group schedule. Since we're describing a home network that will connect to the Internet, you're strongly advised to install a protective firewall program to thwart Internet viruses, worms, or other damaging spyware code. " The typical computer package comes with a CPU unit, keyboard, mouse, and speaker set. That may be just fine for some, but most people require more than that especially in today's "connected" society. Today's users require full multimedia capabilities, a wide range of graphics tools, and accommodations for the various portables we now enjoy.