Key signature

The group of sharps or flats printed after the clef that tells the player which notes are sharpened or flattened throughout the piece.

A key signature saves writing an accidental in front of every affected note and instantly communicates the tonal centre: one sharp means G major or its relative minor, three flats means E flat major or C minor, and so on around the circle of fifths. Guitarists read them less often than pianists because they work from shapes and tab, but the same information is what tells an improviser which scale to use over a progression. Sharps and flats in the signature apply for the whole piece unless cancelled.

Example: A piece with two sharps printed after the clef is in D major or B minor, and every F and C in it is played sharp.

Key signature

See also