A menu key is a physical key on a computer keyboard or other device that brings up a context-sensitive menu on the display. In relation to a computer keyboard, the menu key usually has the same effect as the right mouse button or center mouse button, immediately bringing up a menu specific to the program that is currently active. When the key is on a handheld device, it often can be used to bring up a generic options menu for navigation or can behave in the same manner as the key on a computer keyboard. Certain types of electronic computer hardware, such as monitors, have a menu key that can be used to directly control internal hardware options. Not all computer keyboards or devices have a menu key, and some operating systems or applications do not recognize the menu key even if it is present.
On a computer keyboard, the menu key generally is used to trigger an event that will cause a context menu to appear on the screen. A context menu is a list of options from which the user can select that is related directly to the program that currently has focus. The same menu generally can be triggered by the right mouse button or center mouse button. In addition to causing a menu to appear, the mouse cursor position often is changed to point at the first element in the menu.
The menu key was not part of the original layout of standard computer keyboards. Although the general location has been somewhat standardized, with the key appearing in the bottom right quadrant of the keyboard in many cases, it is not part of a formal layout and so can appear anywhere that is convenient on the keyboard. When the key is pressed, at a programming level, the scancode generated is not within the standard lower-digit scancodes that alphanumeric keys generate, and instead is usually a higher number. Higher-value scancodes were not supported by early computer hardware, making the addition of extra keys difficult or impossible to implement across all systems. Hardware and software progressed, however, to the point where sending extended scancodes was no longer a problem.
Some handheld devices and computer hardware include a menu key to allow a user to easily access a menu to change certain options. In the case of some handheld devices, this key can bring up a context menu or can be used for basic navigation within an operating system. On hardware such as monitors, the key can be used to access hardware-specific functions such as degaussing or frequency changes.