Understanding Compression What It Is and What's Involved Downloading files from the Internet has always been one of the most popular activities on the Internet - third to sending email and browsing the web. We download files from software libraries, ftp directories, YouTube and Google Video, MP3 sites, and we download files sent to us as email attachments. Apple's Macintosh computer was among the first of a couple systems to establish a user-to-hardware relationship through a user-friendly interface. Today, we have quite a few operating systems. Some of the more popular ones are Windows Vista, Mac OS X, ZETA, IBM, Unix, and Linux. But even still, operating systems have extended onto to non-computer devices such as game consoles, portable music players, and PDAs. So you should install a firewall on the computer that grants access to the computer, and then install an anti-virus and anti-spyware program on each of the remaining computers in the network. If you have files that shouldn't be shared (bank statements, credit card information, etc.), you can restrict their access in one of several ways. An Introduction to File Extensions In an effort to be "user-friendly," Windows (and perhaps some other operating systems) hides the most important part of a file name from new computer users: the extension. Okay - we're assuming that the reasoning behind hiding extensions is a "user-friendly" one because we just can't come up with any other reason for hiding them. 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. A virus that attaches itself to (infects) other programs is a file virus and activates the moment that an infected program starts. File viruses may also be referred to as parasitic viruses, however should a virus work from both the boot-sector and from an infected program, the virus is then known as a multipartite virus. 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. A disk drive that's clogged with unnecessary and unused files is disk drive that works harder than it has to. Although Window's defrag system can ease some of the stress that these files place onto the drive, it doesn't do much to get rid of the problem in the first place.