Checkboxes

Checkboxes are used to set options with clear opposites to "on" or "off." A checked checkbox should mean the option is "on." An unchecked checkbox should mean the option is "off." Checkboxes can be used to set one or more options to on or off (see Figures 10 and 11).

Figure 10. Single checkbox option

Figure 11. Yahoo.com multiple checkbox options

Usability problems

Unclear opposites

Users should immediately understand the consequence of a checked or unchecked checkbox. To avoid confusion, use labels that are clear opposites (for example, Yes/No, On/Off, Subscribe/Unsubscribe). If the label doesn't have a clear opposite, use radio buttons instead where options should be related, but not necessarily opposites.

Codependent checkboxes

Each checkbox in a group of checkboxes can be turned to "on" or "off," however, changing the state of one checkbox should not change the state of other checkboxes in the group. This practice violates the principle that checkboxes are independent controls.

Long lists

Long lists of checkboxes are difficult to scan. To improve readability, subdivide long lists into smaller groups of nine or fewer options. Use subheadings to label each group. Consider using a multiselect list box if there are no logical subgroups.