A checkbox is a graphical user interface element that permits the user to make a binary selection.
A checkbox is a graphical user interface element that permits the user to make a binary selection. Checkboxes are often shown on the screen as a square box that can contain white space (for false) or a tick mark or X (for true). 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.
Source: http://en.wikipedia.org/wiki/Checkbox
Some applications optionally allow a third state of Null, usually indicated by a grayed-out appearance. A similar provision is often made for a new record which has no instantiated values.
Here is an example of HTML code to present a checkbox in a user-entry form:
<input type="checkbox" name="example" value="foo">foo
- The checked attribute is a boolean attribute.
- When present, it specifies that an element should be pre-selected (checked) when the page loads.
- The checked attribute can be used with
<input type="checkbox">and<input type="radio">. - The checked attribute can also be set after the page load, with a JavaScript.
