key (music)

In music, describes any piece where the melodies and harmonies are based on the notes of a major or minor scale. For example, a piece in the key of C major uses mainly the notes of the C major scale, and the harmonies are made up of the notes of that scale. The first note of a scale is known as the tonic and is the note that tells us the name of the key.

Most music which uses this system (known as the key system or tonal system) does not remain in one key, but moves to related keys in a process known as modulation. This adds contrast and creates tension, which is relieved when the music returns to the ‘home’ or tonic key.

The term is also used for the lever on keyboard instruments, such as the piano or organ, which the player presses in order to produce a note; and for the levers on woodwind instruments which players press to cover the note holes beyond the reach of their fingers.