Radio button
![](https://upload.wikimedia.org/wikipedia/de/d/dc/Radiobuttons.gif)
A radio button (also option field , also erroneously multiple option box or radio button ) is a control graphical user interfaces , which is used to select exactly one option from several.
functionality
![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/61/BlaupunktRadio1954.jpg/220px-BlaupunktRadio1954.jpg)
Radio buttons are usually below, sometimes next to each other, small circles, followed by short descriptive texts. The circles can have two states: unmarked (empty ) and marked (with a dot in the middle
). Only one of several radio buttons in a group can be selected. As soon as a radio button is marked, any marking of another radio button in the same group is deleted. The initial state can either be that a specific radio button or not a single radio button is preselected.
The name radio button comes from the fact that this behavior is similar to the mechanical buttons that used to be used on radios . If one of these keys is pressed, it engages and at the same time the previously pressed key is released.
On the computer, the selection process must usually be completed by pressing a confirmation button .
Demarcation
The similarly designed checkboxes not only allow you to select one item from the list, but any number.
programming
In the mostly hierarchical GUI toolkits , those radio buttons that are assigned to the same group, usually visualized by a labeled frame, are mutually exclusive (see screenshot). Radio buttons can be generated in HTML with several elements of the type (for example ) for integration on websites . Radio buttons that belong together and are therefore mutually exclusive must be marked with the same name. XForms uses radio buttons to display elements when the full appearance ( ) has been selected.
input
radio
<input type="radio" name="farbe" value="rot" />
select1
appearance="full"