Blues forms — 12, 8 and 16 bars, minor and jazz
The blues is a family of forms, not one grid. Learn the basic 12-bar first, then the variants — each is a small edit to the same sentence: make a statement, repeat it somewhere less stable, then answer it and come home.
The basic 12-bar
Three four-bar phrases. Lyrically it's AAB: sing a line (bars 1–4), sing it again over the IV (bars 5–8), then answer it (bars 9–12). Harmonically, bar 9 is the form's emotional peak — the V7 is the question, and everything after it is the answer.
The quick change
Identical, except bar 2 jumps to the IV7 and back. It makes the opening phrase restless instead of patient, and it's so standard that at a jam someone will simply say "quick change in A".
The 8-bar blues
A tighter sentence — statement and answer with no repeat. Key to the Highway is the template most players learn; How Long Blues and It Hurts Me Too live in the same family. Notice it reaches the V by bar 2: the 8-bar form spends most of its life answering.
The 16-bar blues
Usually a 12-bar with one phrase doubled — eight bars of I before the IV arrives, or the answer phrase repeated like a preacher restating the punchline. Herbie Hancock's Watermelon Man is a famous funky 16-bar blues built exactly that way.
The minor blues
Swap dominant tonality for minor 7ths and the mood goes from raucous to haunted. The signature move is bars 9–10: instead of V–IV, the minor blues slides ♭VI7 → V7 — chromatic drama. The Thrill Is Gone (B minor) is the canonical study.
The jazz blues
Same skeleton, denser connective tissue: jazz keeps the three pillars but fills the gaps with ii–V motion and a passing diminished, so the harmony always leans somewhere. This is the bridge to the jazz deep dive.