bmp - This extension indicates another image file that might have originated from Windows Paint program. .dll - This extension indicates a Dynamic Link Library which may contain additional programming code for software. Many different programs often share Dynamic Link Libraries and you'll find a bunch of them in the Windows/System directory (but don't ever delete them)! Sometimes, the data comes from an outside source like the Internet or the computer that the program runs on. The data that a program receives is called input and data that the program generates is called output. Other times, the data is unknown. If the program were working with a simple algebra equation like, "x + 5 = y," the variables "x" and "y" would be unknown pieces of data. So much so, that even some well known software development corporations have joined the cause and built a few freeware open source products of their own! If you can remember that there are hoards of alternatives to costly commercial software (and you make the effort to get it), you'll discover that you can keep up with the rest of the computer industry at a significantly cheaper cost than if you attempted to pay your way down the software aisle. Or if you were to uninstall a graphics-editing program, all the pictures you made with the program would become orphan files. 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. Viruses that destroy data are known as Trojan horses, viruses that explode their attacks are called bombs, and viruses that duplicate themselves are called worms. Some viruses are a combination of each, however they can be further identified according to where they're located on a computer. A virus originating from the boot sector of a computer is a boot-sector virus and this nasty devil does its dirty work the moment a computer is turned on. Perhaps at this point you're wondering where you can get in on this wonderful opportunity. There are plenty of open source opportunities sprinkled across the Internet and they can be easily found though any search engine. Google "open source project" and you'll be sure to find more resources than you can shake a stick at!