A chromatic scale is a scale that contains twelve pitches, or notes, each separated by a half step (semitone) from its adjacent pitches. That is, it consists of all the seven pitches of an octave plus all of the intervening sharps and flats. This contrasts with major and minor scales, in which some of the intervals between pitches are a half step but others are a whole step. In terms of a piano keyboard, the C major scale, for example, would consist of all seven white keys from one C to the next higher C (or eight including the higher C), whereas the corresponding chromatic scale would consist of all twelve keys between them, both the seven white and the five black keys.
The word chromatic comes from the Greek word chroma meaning color. Every other scale or chord in most Western music is derived from the chromatic scale. Most classical Western music is built around the major and minor scales, but chromatic scales are often used in atonal music and jazz as well as in some Asian music.