Navigation Buttons

In computing, a button (sometimes known as a command button or push button) is a widget that provides the user a simple way to trigger an event, like searching for a query at a search engine, or to interact with dialog boxes, like confirming actions.
A typical button is a rectangle, wider than it is tall, with a descriptive caption in its center.

The most common method of pressing a button is clicking it, but other input such as keystrokes can be used. When pressed, in addition to performing a predetermined task, buttons often undergo a graphical change to look as if they were being temporarily depressed.

Some very common incarnations of the button widget are:

An OK Button for confirming actions
A Cancel button for cancelling actions (e.g., closing windows)
An Exit button for closing programs
Buttons are also used for many narrative descriptions of how to use events in Adobe Flex. A button object is instantiated as well as a label which displays "Button Clicked" once the button has been pressed.

On the World Wide Web, the term "button" (aside from the 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, like Wikipedia itself, often have a "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 the blogosphere