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.

If the scale is tuned such that the interval between any two adjacent notes may function both as a diatonic and chromatic semitone (as in the modern 12-tone equal temperament), it provides a practical approximation of acoustically pure intervals in every key, and serves as a superset containing subsets like diatonic scales.

Chromatic instruments, such as the piano, are made to produce the chromatic scale. Other instruments capable of continuously variable pitch, such as the trombone and violin, can also produce microtones, or notes between those available on a piano.