A
radio button or
option button is a type of
graphical user interfaceA graphical user interface is a type of user interface item that allows people to interact with programs in more ways than typing such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment with images rather than...
elementGraphical user interfaces, also known as GUIs, offer a consistent visual language to represent information stored in computers. This makes it easier for people with little computer skills to work with and use computer software...
that allows the user to choose only one of a predefined
setIn computer science, a set is an abstract data structure that can store certain values, without any particular order, and no repeated values. It is a computer implementation of the mathematical concept of a finite set....
of options. They were named after the physical buttons used on older
car radiosCar audio/video , mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. Such devices aren't necessarily limited to automobiles, and can be used, marketed, or manufactured for marine, aviation, and mass transit...
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.
A
radio button or
option button is a type of
graphical user interfaceA graphical user interface is a type of user interface item that allows people to interact with programs in more ways than typing such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment with images rather than...
elementGraphical user interfaces, also known as GUIs, offer a consistent visual language to represent information stored in computers. This makes it easier for people with little computer skills to work with and use computer software...
that allows the user to choose only one of a predefined
setIn computer science, a set is an abstract data structure that can store certain values, without any particular order, and no repeated values. It is a computer implementation of the mathematical concept of a finite set....
of options. They were named after the physical buttons used on older
car radiosCar audio/video , mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. Such devices aren't necessarily limited to automobiles, and can be used, marketed, or manufactured for marine, aviation, and mass transit...
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.
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). Adjacent to each radio button is normally shown a caption describing the choice that this radio button represents. When the user selects a radio button, any previously selected radio button in the same group becomes deselected. Selecting a radio button is done by clicking the
mouseIn computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...
on the button, or the caption, or by using a
keyboard shortcutIn computing, a keyboard shortcut or hotkey is a finite set of one or more keys that invoke a software or operating system operation when triggered by the user....
.
It is possible that initially none of the radio buttons in a group are selected. This state cannot be restored by interacting with the radio button widget (but it may be possible through other user interface elements). The Apple Human Interface Guidelines specify that one item of a radio button group must always be selected.
When used in an
HTMLHTML, which stands for Hyper Text Markup Language, is the predominant markup language for web pages. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists etc as well as for links, quotes, and other items. It allows images...
formA webform on a web page allows a user to enter data that is sent to a server for processing. Webforms resemble paper forms because internet users fill out the forms using checkboxes, radio buttons, or text fields...
, if no button in a group is checked, then no name-value pair is passed when the form is submitted. For example, for a radio button group named Gender with the options Male and Female, the variable Gender would not be passed, even with a blank value.
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