Key (music)

Key (music), in Western music, system of related tones based on the central tone in the musical scale being used. The keynote, or tonic, of a piece of music is the tone around which its melodies and harmonies are organized. Works and passages are thus said to be “in a certain key.”

There are 24 keys in total. There are two types, or modes, of keys: major and minor. The key is indicated in the key signature, which is the arrangement of sharps and flats at the beginning of a line of music. This key signature defines the pitch of the composition. A musical piece usually begins and ends in the same key, but other keys may be used in parts of the work. Moving from one key to another is called modulation. Since the 16th century, keys have been associated with certain emotional or evocative qualities. Major keys are said to indicate happiness and brightness, whereas minor keys denote sadness and darkness.

The term key also refers to the levers of certain musical instruments, such as the piano and the organ. When these keys are depressed, they produce the instrument’s musical tones. In wind instruments, such as flutes and clarinets, the keys are the levers that cover the air holes.