In computer terminology, an icon is a small picture that represents an object, a program, or some other specific item that is relevant to the user. Icons are a principal tool of graphical user interfaces. On a Web page, an icon is typically a graphical image that links the page with another Web page.

Expressed in programming language, an icon is a bitmap (a representation, consisting of rows and columns of dots, of an image) with a maximum size of 32 x 32 pixels (short for picture element, a pixel is a single point in an image). Icons have an extension of .ico to the file name.

Icons are useful in applications involving windows. Entire windows can be minimized into a small icon by using the mouse to click on the appropriate command box in the window. Conversely, an icon can be restored to the original window by clicking on the appropriate box of the icon, again using the mouse.

Icons can be moved around on the computer display screen as if they were real objects on a real desktop. Thus, the virtual desktop can be tailored to the functional preferences of the user.