Microsoft Windows XP Home or Professional is an operating system , a computer program that controls the basic operation of your computer and the programs you run. A program , also known as an application, is task-oriented software you use to accomplish a specific task, such as word processing, managing files on your computer, or performing calculations. Windows XP displays programs in rectangular frames on your screen, called windows (thus the name of the operating system). A window can contain the contents of a file and the application in which it was created, icons (picture representations of a program or a file), or other usable data. A file is a collection of information (such as a letter or list of addresses) that has a unique name, distinguishing it from other files. This use of windows and icons is called a graphical user interface ( GUI , pronounced "gooey"), meaning that you ("user") interact ("interface") with the computer through the use of graphics: icons and other meaningful words, symbols, and windows.