A keyboard instrument is a musical instrument played using a keyboard, a row of levers that are pressed by the fingers. The most common of these are the piano, organ, and various electronic keyboards, including synthesizers and digital pianos. Other keyboard instruments include celestas, which are struck idiophones operated by a keyboard, and carillons, which are usually housed in bell towers or belfries of churches or municipal buildings.

A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument. 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. Pressing a key on the keyboard makes the instrument produce sounds—either by mechanically striking a string or tine, plucking a string (harpsichord), causing air to flow through a pipe organ, striking a bell (carillon), or activating an electronic circuit. Since the most commonly encountered keyboard instrument is the piano, the keyboard layout is often referred to as the piano keyboard or simply piano keys.