Key signatures: sharps
Learn the sharp keys G, D, A and E and the order in which sharps appear.
Key signatures
Writing a sharp before every F in G major would be tiresome. So the signs of a key are written once, right after the clef. This is the key signature: it applies to every note of that letter, in every octave, until the end of the piece.
A key is the scale a piece is built on, with its tonic. The key signature shows which key the music is in.
G major: a sharp on the F line after the clef makes every F sharp
A key signature is cancelled only by a natural, and only until the end of the bar.
Practice: Which key?
Practice: Melodic dictation in G major
The order of sharps
Sharps appear in a key signature always in the same order: F, C, G, D, A, E, B. G major has one sharp, F♯; D major two, F♯ and C♯; A major three; E major four.
D major: F♯, C♯
A major: F♯, C♯, G♯
E major: F♯, C♯, G♯, D♯
How to tell the key from the sharps. Find the last sharp in the key signature and go up a semitone: that is the tonic. Last sharp C♯: tonic D. Last sharp G♯: tonic A.
Each next key starts a fifth higher than the one before: C → G → D → A → E, gaining one sharp each time.