Cross-Reference

If you’re an experienced Windows user and want some specifics on
what’s new in Windows XP, see Appendix B.
For those of you who are new to the game, let’s start by pointing out that Microsoft Windows XP is a
computer program. Specifically, it’s a type of program known as an operating system, often abbreviated
OS. You may have heard of some of the other operating systems out there, such as DOS, the Mac OS
used on Macintosh computers, and Linux and UNIX, used mainly in large businesses.
One thing that makes the OS different from all other programs available for PCs is that an OS is
required to make your system work. A computer without an OS is like a car without an engine. Turning
on a computer that has no operating system installed leads to nothing but a message on the screen
telling you there is no operating system installed.