A
musical keyboard is the set of adjacent depressible levers or keys on a
musical instrument, particularly the
piano. Keyboards typically contain keys for playing the twelve notes of the Western
musical scale, with a combination of larger, longer keys and smaller, shorter keys that repeats at the interval of an
octave. Depressing a key on the keyboard causes the instrument to produce sounds, either by mechanically striking a string or tine (
piano,
electric piano,
clavichord); plucking a string (
harpsichord); causing air to flow through a pipe (
organ); or strike a bell (
carillon). On electric and electronic keyboards, depressing a key connects a circuit (
Hammond organ,
digital piano,
synthesizer). Since the most commonly encountered
keyboard instrument is the piano, the keyboard layout is often referred to as the "piano keyboard".