In computing, a keyboard is a typewriter-style
keyboard, which uses an arrangement of buttons or
keys, to act as mechanical levers or electronic
switches. Following the decline of punch cards and
paper tape, interaction via teleprinter-style keyboards
became the main input device for computers.
Despite the development of alternative input devices,
such as the mouse, touchscreen, pen devices, character
recognition and voice recognition, the keyboard
remains the most commonly used and most versatile
device used for direct (human) input into computers.
A keyboard typically has characters engraved or
printed on the keys and each press of a key typically
corresponds to a single written symbol. However,
to produce some symbols requires pressing and holding
several keys simultaneously or in sequence. While
most keyboard keys produce letters, numbers or signs
(characters), other keys or simultaneous key presses
can produce actions or computer commands.
In normal usage, the keyboard is used to type text
and numbers into a word processor, text editor or
other program. In a modern computer, the interpretation
of key presses is generally left to the software.
A computer keyboard distinguishes each physical
key from every other and reports all key presses
to the controlling software. Keyboards are also
used for computer gaming, either with regular keyboards
or by using keyboards with special gaming features,
which can expedite frequently used keystroke combinations.
A keyboard is also used to give commands to the
operating system of a computer, such as Windows'
Control-Alt-Delete combination, which brings up
a task window or shuts down the machine. Keyboards
are the only way to enter commands on a command-line