View source for Checkbox

{{Short description|Element of graphical user interfaces}}
{{About|the computer interface element|the concept in US tax law|Check-the-box}}
{{Refimprove|date=November 2010}}
[[File:Checkbox2.png|thumb|Sample binary-state checkboxes, with some options disabled]]

A '''checkbox''' ('''check box''', '''tickbox''', '''tick box''') is a [[graphical widget]] that allows the [[user (computing)|user]] to make a binary choice, i.e. a choice between one of two possible mutually exclusive options. For example, the user may have to answer 'yes' (checked) or 'no' (not checked) on a simple [[yes–no question|yes/no question]].

Checkboxes are shown as empty boxes when unchecked, and with a [[check mark|tick]] or [[cross]] inside (depending on the graphical user interface) when checked. A caption describing the meaning of the checkbox is normally shown adjacent to the checkbox. Inverting the state of a checkbox is done by clicking the mouse on the box, or the caption, or by using a [[keyboard shortcut]], such as the [[space bar]].

Often, a series of checkboxes is presented, each with a binary choice between two options. The user may then select several of the choices. This is contrasted with the [[radio button]], in which only a single option is selectable from several mutually-exclusive choices.

Checkboxes may be disabled (indicated "[[greyed out]]") to inform the user of their existence and possible use despite momentary unavailability.

==Tri-state checkbox==
[[File:Checkbox States.svg|thumb|Sample tri-state checkboxes]]
Some [[Application software|applications]] use checkboxes that allow an [[Three-valued logic|indeterminate state in addition to the two]] provided by a normal checkbox.{{Citation needed|date=March 2022|reason=Which implementations?}} This third state is shown as a square or dash in the checkbox, and indicates that its state is neither checked nor unchecked. This is most often used when the checkbox is tied to a collection of items in mixed states. The indeterminate state cannot usually be selected by the user, and switches to a checked state when activated.

For example, a checkbox presented to select files to send via [[File Transfer Protocol|FTP]] might use a [[tree view]] so that files can be selected one at a time, or by folder. If only some of the files in a folder are selected, then the checkbox for that folder would be indeterminate. Clicking on this indeterminate checkbox would select all or, less commonly, none of the contained files. Continuing to click on the checkbox would alternate between checked (all sub-directories and files selected) and unchecked (no sub-directories or files selected).{{Image requested inline}}

Some tri-state checkbox implementations{{Citation needed|date=March 2022|reason=Which implementations?}} allow the user to toggle among all states, including the indeterminate state, by remembering the mixed state of the items in the collection. This serves as an [[undo]] feature.

==Not actionable==
Setting or clearing ("[[unclick]]ing") a checkbox changes the checkbox's state with no other side-effects. Violating this guideline by associating additional actions with the change of state frequently confuses users, because they are used to configuring data in entry controls such as text boxes, radio buttons, and checkboxes and then invoking an action control such as a push button to initiate the action to process the data.<ref>{{cite web |url=http://msdn.microsoft.com/en-us/library/dn742401.aspx |title=Check Boxes |website=msdn |access-date=February 5, 2010}}</ref><ref>{{cite web |last1=Nielsen |first1=Jakob |url=http://www.useit.com/alertbox/20040927.html |title=Checkboxes vs. Radio Buttons |website=Jakob Nielsen's Alertbox |date=September 2004 |access-date=February 5, 2010 |archive-date=August 29, 2012 |archive-url=https://web.archive.org/web/20120829012515/http://www.useit.com/alertbox/20040927.html |url-status=dead }}</ref>{{Clarify|date=March 2022|reason=Big sentence is difficult to read}}

One common exception is to enable or display additional user input elements whose relevance depends on the checkbox state. In other situations [[Toggle switch (widget)|toggle switch]] is typically used instead of a checkbox.

==HTML==
In [[form (web)|web forms]], the [[HTML element]] {{code|lang=html|code=<input type="checkbox">}} is used to display a checkbox.<ref>{{cite web
|title=&lt;input type<nowiki>=</nowiki>"checkbox"&gt; - HTML: HyperText Markup Language {{!}} MDN
|url=https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input/checkbox
|website=developer.mozilla.org
|publisher=[[Mozilla]] |access-date=19 September 2023 |date=13 June 2023}}</ref>

==Unicode==
{{plainlist|
*{{unichar|2610|BALLOT BOX |size=150% |ulink=Universal Character Set characters |nlink=Ballot box |note= }}
*{{unichar|2611|BALLOT BOX WITH CHECK |size=150% |nlink=Check mark |note= }}
*{{unichar|2612|BALLOT BOX WITH X |size=150% |nlink=X mark |note= }}
}}

==See also==
* [[Tick-box culture]]
* [[Radio button]]
* [[Toggle switch (widget)]]
* [[Boolean data type]]

==References==
{{Reflist}}

==External links==
*{{Commons category-inline|Check boxes}}

{{Graphical control elements}}

[[Category:Graphical control elements]]