Clefs
Four clefs, one principle: each puts one particular note on one particular line, and everything else follows. All 4 at a glance.
Five lines on their own say nothing. Only a clef at the start of the line decides which note sits where — and that is exactly why there are several: a double bass and a flute would need so many ledger lines in the same clef that nobody could read them.
The names say what the sign does. The G clef puts G above middle C on the second line, the F clef puts F below middle C on the fourth, the C clef puts middle C on the third or fourth. The rest follows: lines and spaces are a ladder without gaps.
The four clefs
Anotona does this for you
Photograph a page of sheet music or play the melody — Anotona finds the key, engraves the notes and transposes them into any other. Free.
See AnotonaEvery note on this page is computed, not typed in — following the rule that also makes F# major spell its seventh degree E#, not F.