sit format (if you're using a Mac). The two most popular software programs used to compress and decompress files are Winzip and StuffIt respectively. There are other programs that do the same thing and there are even programs that can compress and decompress files for both the Windows and the Mac system. The smart thing to do when you don't want to lose the data that you created with an unwanted program is to: 1. Save or convert your documents to a format that will work with different program first (that is, a program that you intend to keep) 2. Archive them onto a floppy disk, flash drive, or CD-ROM 3. When Windows was developed, the need for typing commands was essentially eradicated thanks to the introduction of the point-and-click (mouse) interface. But this didn't stop the batch file fever that started under MS-DOS - and in some small circles, batch files are still as popular as they were in the beginning. We tried to convince him that a fully functional computer is one that is personalized with specially selected hardware and software accessories - and that the computer purchased at the store doesn't come with these things. Unfortunately, all of our convincing was to our avail. Our client insisted that he should never need more than what came with his boxed product and that we were just trying "bilk" more money out of him. Commands are the instructions that a computer follows to perform an action. 2 To make them work inside of a program, programmers assign commands to objects like buttons for example. The commands in a program are pretty useless unless they have some data to act on so programmers either give the programs some data to work with (list of names or numbers for example) or they make the program generate it's own data. You may find yourself in need of more hard drive space for all those videos and mp3s that you download, for example. Or maybe that cool new programming language you've been dying to try requires more memory than what your computer currently has. Unless the activities on your computer are restricted to pure textual output (plain text files), your computer is going to get filled with a lot of "stuff" - stuff that can overfill a PC's capacity too much for the computer to function well.