Mouse keys is a feature of some graphical user interfaces that uses the keyboard (especially numeric keypad) as a pointing device (usually replacing a mouse). Its roots lie in the earliest days of visual editors when line and column navigation was controlled with arrow keys. Today, mouse keys usually refers to the numeric keypad layout standardized with the introduction of the X Window System in 1984.

Historically, MouseKeys supported GUI programs when many terminals had no dedicated pointing device. As pointing devices became ubiquitous, the use of mouse keys narrowed to situations where a pointing device was missing, unusable, or inconvenient. Such situations may arise from the following:

In 1987, Macintosh Operating System 4.2 Easy Access provided MouseKeys support to all applications. Easy access was (de)activated by clicking the ⇧ Shift key five times.^{[citation needed]}

By the early 2020s, with graphics tablets becoming more common, a configuration change may be required before enabling MouseKeys.^{[citation needed]}

The X Window System MouseKeysAccel control applies action (usually cursor movement) repeatedly while a direction key {1,2,3,4,6,7,8,9} remains depressed. When the key is depressed, an action_delta is immediately applied. If the key remains depressed, longer than mk_delay milliseconds, some action is applied every mk_interval milliseconds until the key is released. If the key remains depressed, after more than mk_time_to_max actions have been applied, action_delta magnified mk_max_speed times, is applied every mk_interval milliseconds.

The first mk_time_to_max actions increase smoothly according to an exponential.

${\displaystyle \mathrm {action\_delta} \times \mathrm {mk\_max\_speed} \times \left({\frac {i}{\mathrm {mk\_time\_to\_max} }}\right)^{\frac {1000+\mathrm {mk\_curve} }{1000}}}$

These five parameters are configurable.