Chromatic scale

In Western music, a chromatic scale (or twelve-tone scale) is a set of twelve pitches within an octave, where the interval between any two adjacent notes is a semitone.

The chromatic scale is a common layout of pitches for fixed-pitch instruments such as the piano and guitar, which are called chromatic instruments. Other instruments capable of continuously variable pitch, such as the trombone and violin, can also produce microtones, or intervals smaller than a semitone.

Chromatic scales may be tuned in several different ways. The most common tuning system is 12-tone equal temperament, which divides the twelve pitches evenly. In this system, diatonic scales are available above every tone, and interval relationships are consistent.