In composing music, you follow certain rhythm forms. These musical forms outline placement for accented and unaccented beats that form a pattern for a passage or for a whole piece. The following list offers a handy guide to the different parts in different types of compositions:
One part form: A, AA, AAA, and so on
Binary form: AB, AABB
Ternary/tertiary form: ABA, AABA
Arch form: ABCBA
Sonata: ABA
Rondo: ABACADAEAF
8-bar blues: I, IV, I, VI, ii, V, I, V/I (turnaround)
12-bar blues: I, I, I, I, IV, IV, I, I, V, IV, I, V/I (turnaround)
16-bar blues: I, I, I, I, IV, IV, I, I, V, IV, V, IV, V, IV, I, V/I (turnaround)
24-bar blues: 8xI, 4xIV, Ix4, V, V, IV, IV, I, I, I, V/I (turnaround)
Verse-chorus form (pop music): Intro ABACBCB