Keyboard

• Alphanumeric keyboards (including the typewriter keyboard, the generic computer keyboard and its descendant the IBM PC 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