Button (computing)

In computing, a button (sometimes known as a command button or push button) is a widget which provides the user a simple way to trigger an event, such as clearing the display on a calculator program. Buttons are also used to provide the user ways to respond to dialog boxes.

A typical button is a rectangle, wider than it is tall, with a descriptive caption in its center. The most common method of 'pushing' a button is clicking it, but other input such as keystrokes can be used. When 'pushed', in addition to performing a predetermined task, buttons often undergo a graphical change to look as if they were being temporarily depressed.

Very common uses for the button widget:

• An OK Button for confirming actions
• A Cancel button for cancelling actions
• An Exit button for closing programs.

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In World Wide Web, the term "button" (aside of command buttons found in HTML forms) also refers to button graphics, which are typically used to advertise programs that were used to create or host the site (for example, MediaWiki sites often have "Powered by Mediawiki" button on the bottom right corner of the page), or programs that are recommended to view the site. The buttons are linked to the advertised sites. These were first popularized by Netscape and Microsoft during the browser wars.

Button graphics are typically 88x31 pixels in size, but recently, smaller 80x15 pixels buttons have become very popular in weblog world.