A radio button or option button is a type of graphical user interface element that allows the user to choose only one of a predefined set of options. They were named after the physical buttons used on older car radios to select preset stations - when one of the buttons was pressed, other buttons would pop out, leaving the pressed button the only button in the "pushed in" position. Although sometimes called "radial" buttons because of their circular shape, this name is incorrect. The buttons were named for their behavior, not their shape.