Any key refers to a command prompt that will be fulfilled no matter which keyboard button is pressed, and is most often seen on early operating systems that were released before mice became common. "Press Any Key" does not refer to a button labeled "Any" on the keyboard, and because of this has become a joking reference to the confusion of new computer users. The Compaq FAQ has been known to contain the answer to this seemingly obvious question.
The confusion over the Any key dates back at least to the days of the ZX Spectrum where "Press any key to continue" was often used as a way to ensure programs did not continue operation without gaining the user's attention. The computer would then wait for an arbitrary key to be pressed by the user before continuing execution.
A few new users were confused by this reference to the Any key and began wondering where the "any" key was on the keyboard. The confusion is much less common now as some computer help systems have added explicit explanations of this problem. Many computer manuals and computer programs now make other language choices to prevent this confusion, including suggesting a particular key to press such as the space bar. This may be a more user-friendly suggestion, since in many situations where any key is requested to be pressed, including the DOS
pause command, some modifier keys such as Shift and Alt have no effect at all whereas others, such as Esc and Ctrl-C, can have an undesired effect, such as quitting the program. With the rise of GUI operating systems, this problem has also diminished, because user gestures are now often done with a mouse rather than a keyboard, allowing most programs to refrain from instructing users to use the keyboard.
On some models, if the keyboard is unplugged, the command prompt that appears is, "Keyboard not detected. Press any key to continue". Pressing the left mouse button should overcome this paradox.
A common joke in computing involves a person who is inexperienced in the use of computers asking where to find the Any key on the keyboard.
Unusually, the Remote Controller on the Samsung DVD Recorder Model DVD-HR735 has an 'ANYKEY'.
Some shops actually sell any keys only as a decoration on a keyboard.
In an episode of The Simpsons, Homer Simpson is working on a computer which prompts him to press "any key". He then searches for the nonexistent "Anykey". When this task proves to be too much work for him and he presses the "tab" key (expecting a Tab soda to come out the disk drive), the computer proceeds. This gag was also used in the film The Adventures of Rocky and Bullwinkle. It is also used in a StarCraft: Brood War mission towards the end of the Terran campaign when a marine attempts to operate an enemy computer.
In Russian computer slang term 'Anykeyschik' (Эникейщик) is used to describe a low-grade computer technician implying that his job consists of pressing 'any key' when necessary.