12 Bar Blues Progression

The standard 12 bar blues progression, and variations on its theme, is the basis for all blues music, some jazz, and many rock & roll songs. A classic example of a blues rock song would be "You Shook Me" by Led Zeppelin.

The progression is composed of the one, four, five chords (I, IV, V) in any key. These chords are all dominate 7th chords. The progression is:

4 bars of the I chord
2 bars of the IV chord
2 bars of the I chord
1 bar of the V chord
1 bar of the IV chord
2 bars of the I chord

So in the key of C, for example, it would be:

C7  C7  C7  C7
F7  F7  C7  C7
G7  F7  C7  C7