In computing, a keyboard is a peripheral partially modeled after the typewriter keyboard.Physically, a keyboard is an arrangement of buttons, or keys. A keyboard typically has characters engraved or printed on the keys; in most cases, each press of a key corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself. See input method editor.
A majority of all keyboard keys produce letters, numbers or signs that are appropriate for the operator’s language. Other keys can produce actions when pressed, and other actions are available by the simultaneous pressing of more than one action key. (wikipedia.org)