14 Mar 2011, 22:55
KEYS
Keyboard. In the context of computers, an electromechanical device which consists of an array of independent movable surfaces - pushbutton switches known as keys - which can be pressed by human fingertips in order to input data. Computer keyboards are modelled after typewriter keyboards, which were mechanical text-entry devices.
Key. A sprung or touch-sensitive electric pushbutton, usually marked with a symbol of some sort, which sends a signal to a computer when pressed or touched. This signal may enter information into the computer or cause it to perform a certain operation. Keys are arranged in specific patterns in an assembly to form a keyboard.
Keystroke. The action of a human being pressing down and releasing a key.
Alphanumeric key. A key which, when pressed, produces a letter of the alphabet or a numeral.
Space bar. A long wide key at the bottom of a keyboard, which produces a space character when pressed.
Return key. A key which issues a "carriage return" when pressed. This is analogous to an old mechanical typewriter: the cursor moves down one line, and all the way to the left. (at least with left to right alphabets)
Enter key. Sometimes synonymous with return, but technically slightly different. On a spreadsheet, for example, pressing the Return key confirms the current text entry and moves the highlighted cell down a row. Pressing the Enter key confirms the current text entry but doesn't usually move the highlighted cell.
Escape or esc key. A key in the upper left corner which has various meanings depending on the application in use. It might mean quit, cancel, end, or close, for example. Bright red escape keys are popular add-on extras with a certain type of geek.
Backspace. A key which deletes the character immediately to the left of the insertion point. Confusingly Macs usually have keys marked delete which actually issue a backspace command.
Delete. Or forward delete, or del. A key which deletes the character immediately to the right of the insertion point. On some keyboards, INS and DEL switched a terminal between text insertion mode and text overwriting mode. The point here is that different keyboards use DEL or Delete to refer to a number of different things.
Cursor keys. Keys which move text insertion points one character in one of four directions.
Arrow keys. See cursor keys.
Function key. A key on a keyboard which can be used to trigger a command or instruction. Most keyboards have a row of keys along the top edge, numbered F1 through F16 or so, which can serve as function keys. Sometimes these are linked to specific actions, such as copying text or ejecting a disc. Sometimes the keys are half-height to save space.
Fkey. See Function key.
Macro keys. Generally speaking, programmable keys on a keyboard which can be used to trigger sequences of other keys, or run programs, etc. Some software may allow Fkeys to be used as macro keys, for example.
Modifier key. A key you press to modify the output of another key. For example, the shift key turns a lowercase letter into uppercase when pressed. Pressing a modifier key alone typically does nothing.
Multimedia key. A key or pushbutton which activates various types of functionality when pressed. These are used by keyboard marketers to differentiate their products from everybody else's. The keys can vary in functionality from useful (speaker controls, mute, play/pause music) to arguably more esoteric (fire up a web browser or mail application).
Shift key. A modifier key which is used to type uppercase letters or access other symbols on the keyboard.
Control key. A modifier key which outputs invisible "control" characters. A throwback to the age of the teletype, really, though on Windows computers control characters are also used as command shortcuts. Typing ctrl-A, for example, might select all text in a document.
Windows key. A key, marked with a trademarked Microsoft Windows flag icon, which enables certain command functions on PCs running versions of Windows since about Windows 95. Analogous to the command key on Macs, or the meta key on UNIX machines.
Command key. On Macs, a modifier key which, when used with alphanumeric keys sends invisible commands to applications, allows for functions such as copy or paste to be performed. Analogous to the Windows key. On early Macs, this key was marked with a square propeller-like symbol. This symbol, incidentally, was derived from Scandinavian road signs where it marks a historical point of interest. On later keyboards, it was marked with both an Apple logo and a propeller symbol. Current keyboards have the word "command" or the abbreviation "cmd" and the propeller.
Alt key. On PCs, a modifier key which performs different functions depending on the application. See Option key.
AltGr key. A modifier seen on some non English language PC keyboards.
Option key. A modifier key on Macs, used for accessing high ASCII characters and other symbols. The key permits Mac users to type diacritical characters or symbols used by Western European languages on a US keyboard, for example. Synonymous with the Alt key.
Fn key. Function: a modifier key on newer Apple keyboards, particularly laptop models. Fn keys switch the function keys from acting as traditional function keys to activating certain Mac features.
Numlock. A feature on some keyboards which switches over certain alphabetical keys on the keyboard to typing numerals. Commonly seen on laptops, numlock effectively creates a virtual keypad.
Capslock. A key, sometimes with a physical latching mechanical lock and sometimes with an electronic button with light, which instructs the keyboard to produce only uppercase letters for all alphabetical characters. Unlike shift it does not alter the output of numeric and other keys.
Scroll lock. An anachronism from the days of terminals - a key which scrolls the window when arrow keys are used, rather than moving the insertion point. A nice idea, but fairly useless today for most users since hardly any programs support the feature.