Keyboard

A keyboard is a data entry or control device using a number of keys which are to be pressed by the fingers. There are two main types of keyboard:

• Alphanumeric keyboards (including the typewriter keyboard, the IBM PC keyboard and generic computer keyboard)
• Musical keyboards

Other types of keyboards, known as "numeric keypads", are the

• Calculator keypad (with the 123 keys near the bottom)
• the CCITT telephone keypad (with the 123 keys at the top), arguably the most common keyboard layout in the world, with roughly 700,000,000 telephones in the world (estimated, as of 1994).

See: Keyboard layout