Thursday, June 11, 2015

Computer keyboard

In computing, a keyboard is a typewriter-style device, 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 maininput device for computers.
A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single writtensymbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce lettersnumbers or signs (characters), other keys or simultaneous key presses can produce actions or execute computer commands.
Despite the development of alternative input devices, such as the mousetouchscreenpen devicescharacter recognition and voice recognition, the keyboard remains the most commonly used device for direct (human) input of alphanumeric data into computers.

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