The piano is a keyboard instrument that produces sound when its keys are depressed, through engagement of an action whose hammers strike strings. Most pianos have a row of 88 black and white keys, representing each note of the chromatic scale as they repeat throughout the keyboard's span of seven and a quarter octaves. There are 52 white keys, known as “naturals”, and 36 black keys, known as “sharps”. The naturals repeat a pattern of whole steps and half steps unique to any given starting note. These patterns define a diatonic scale. The 36 sharps repeat a pattern of whole steps and minor thirds, which defines a pentatonic scale.

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.