Radio button

File:Option-buttons2.gif

Four options on a radio button. When a new option is chosen, the previously chosen option is unselected.

A radio button or option button<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is a graphical control element that allows the user to choose only one of a predefined set of mutually exclusive options.<ref name="micro"/> The singular property of a radio button makes it distinct from checkboxes, where the user can select and unselect any number of items.

Radio buttons are arranged in groups of two or more and displayed on screen as, for example, a list of circular holes that can contain white space (for unselected) or a dot (for selected). Each radio button is normally accompanied by a label describing the choice that the radio button represents. The choices are mutually exclusive; when the user selects a radio button, any previously selected radio button in the same group becomes deselected (making it so only one can be selected). Selecting a radio button is done by clicking the mouse on (or touching the screen over) the button, or the caption, or by using a keyboard shortcut.

Etymology

File:Car Radio of Analog Era.jpg

A radio with a row of five pop-out buttons

Radio buttons are named after the physical buttons that were used on old radios to select preset stations.<ref name="jit">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="micro">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> When one of the buttons is pressed, the other buttons pop out while leaving the pressed one pushed in.

HTML

In web forms, the HTML element <syntaxhighlight lang="html" class="" style="" inline="1"><input type="radio"></syntaxhighlight> is used to display a radio button. Example: <syntaxhighlight lang="html"> <form>

   <input type="radio" name="season" value="winter" id="winter" checked>
   <label for="winter">Winter</label>
   <input type="radio" name="season" value="spring" id="spring">
   <label for="spring">Spring</label>
   <input type="radio" name="season" value="summer" id="summer">
   <label for="summer">Summer</label>
   <input type="radio" name="season" value="autumn" id="autumn">
   <label for="autumn">Autumn</label>

</form> </syntaxhighlight>A group of attributes is defined by name. In one group, only one radio button can be chosen.

Unicode

Version 6 of the Unicode standard includes a character designated to represent a radio button, (🔘) at code point 128,280 (U+1F518), found in the Miscellaneous Symbols and Pictographs section. Similar characters are the mathematical operator Template:Unichar as well as Template:Unichar and Template:Unichar.

The font Wingdings 2 contains at position 153 and 158 glyphs that look like radio buttons.

See also

• Checkbox

External links

• Template:IETF RFC: the HTML 2.0 specification, which defined radio buttons on the web.
• W3 HTML 4.01 Specification
• Usage of radio buttons in Sun's Java Programming Tutorial
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