But without seeing the extension, you wouldn't know it unless you double-clicked on it. The following list defines some of the most common extensions that you'll find on your computer. .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. In fact, by following the simple advice below, you can enjoy the use of your computer to up to five years or more - reserving expenses to simple software upgrades rather then complete and costly hardware upgrades. One of the easiest and least expensive things you can do to extend the life of your computer is to get rid of unnecessary programs, folders, and files. It may contain squares, boxes, words, icons, and buttons. If you're experiencing insufficient memory for example, you might see black rectangles across the user interface of your software programs. Title bar - this is the top-most part of a program that displays its own name or it may describe the contents displayed in another part of the interface. Even ordering a pizza is now a simple matter of dialing from a wireless cell phone and making a few selections from series of pre-programmed menus! The important thing to realize here is that this phenomenon isn't a new convenience - it's a new requirement. And if you haven't jumped onto the binary wagon, you're going to face a few problems. Another benefit that open source brings to light is the speed at which its products are developed, enhanced, supported and distributed. This is because the people who regularly contribute to an open source product do so for unmotivated reasons (other than perhaps to feed the ego.) They're highly talented, they're available, and they care. There are a number of places available including computer store outlets, online stores, auction sites, used computer stores, or your friendly neighborhood yard sale. For the computer novice, we recommend buying a computer from a physical store. In a physical store, you have the opportunity to see the computer of interest in person and ask questions.