Why does a piano have black keys?

The black keys on a piano are there to complete the chromatic scale. The chromatic scale is a musical scale that includes all 12 pitches, from C to B. The white keys on a piano represent the natural notes of the scale, while the black keys represent the sharps and flats.

The sharps and flats are needed to create the different intervals between the notes. For example, the interval between C and D is a whole tone, while the interval between C# and D is a semitone. The semitone is a smaller interval than a whole tone, and it creates a different sound.

The black keys are also used to create chords. A chord is a group of three or more notes that are played together. The different combinations of black and white keys can create a variety of different chords.

The black keys add complexity and richness to the sound of a piano. They make it possible to play a wide variety of music, from classical to jazz to popular.