What is Key Signature?
A key signature is the set of sharps or flats written at the start of each line of sheet music. It shows which notes are raised or lowered throughout the piece and points to its key.
Sharps are always added in the same order (F, C, G, D, A, E, B) and flats in the reverse order (B, E, A, D, G, C, F). G major has one sharp, F sharp; F major has one flat, B flat; C major and A minor have none.
Every key signature is shared by one major key and its relative minor. The signature narrows the key down to those two, and the melody and chords decide which one the piece is really in.
Notes outside the key signature are written with accidentals next to the individual notes.
Example
D major has two sharps, F sharp and C sharp. The same signature is used for B minor.
Put it to work
See the notes, key signature and chords of any key, free.
Scale and Chord Finder