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Caps lock is a key on many computer keyboards. Pressing it sets an input mode in which typed letters are uppercase by default. The keyboard remains in caps lock mode until the key is pressed again. On some computers, holding down the shift key while caps lock is on temporarily switches to lowercase.
People typing case-sensitive passwords that are not displayed verbatim on the screen may not realize that caps lock is on, causing errors. Help guides, tech support materials, and sometimes the interface itself may include advice on checking caps lock before typing a password. In Windows login screens, a warning that caps lock is on is shown in a balloon near the field. In Mac OS X, when caps lock is on, a caps lock symbol (⇪) is displayed inside a password field. Operating systems may also provide audible notifications when caps-lock, num-lock, or scroll-lock buttons are toggled.
Some manufacturers include an option in the controller software to deactivate the caps lock key. This behaviour allows users to decide themselves whether they want to use the key, or to disable it to prevent accidental activation.
The keyboards of many early computer terminals, including the ASR-33 Teletype and Lear-Siegler ADM-3A, and early models of the IBM PC, positioned the Ctrl key where caps lock resides on modern keyboards.
The undesirable attributes of caps lock have led some power users to swap the positions of the two keys using aftermarket modifications; in the same vein, the One Laptop Per Child computers opt to place Ctrl in the caps lock position and discard caps lock entirely. In 2006, Pieter Hintjen launched the CAPSoff campaign with the aim of persuading keyboard manufacturers to stop including the caps lock key.
Although a shift lock key is not the same thing as a caps lock key, it is nowadays rare for a computer to have both. For instance, the Commodore 64 had a shift lock but no caps lock: by depressing the key labeled "Shift Lock", it latched and stayed that way until unlatched, and brought up again. With the Commodore 64, there was no scan code associated with the shift lock key because it served only one purpose—grounding all of the keyscan lines as though the shift key were being pressed.
On modern QWERTY keyboards, though the caps lock mode capitalises letters, it does not affect other keys, such as numbers or punctuation, in the way that the shift key does. A version of caps lock that affects all keys as though it were a shift key does exist on certain layouts such as the French AZERTY and those of some older computers. The origin of the function is found on mechanical typewriters, where the shift key causes the entire type apparatus to elevate upwards, physically shifting to produce capitals and secondary characters.
International Caps Lock Day
- Don Marti (2006-10-27). "Doing it for the kids, man: Children's laptop inspires open source projects". Linux World. Retrieved 2010-06-11.
- Calore, Michael (Aug. 16, 2006). "Death to Caps Lock". Wired. Retrieved Oct. 22, 2010.
- Brian, Matt (October 22, 2010). "Today is INTERNATIONAL CAPS LOCK DAY, but what is it?". Retrieved October 22, 2010.
- Blass, Evan (October 22, 2006). "HAPPY INTERNATIONAL CAPS LOCK DAY". Retrieved October 22, 2010.
- WikiWikiWeb:CapsLockOff—describes how to remap the caps lock key for other purposes.
- CAPSoff Official Website
- Caps lock day official site.