The 12-bar blues is one of the most popular chord progressions in popular music, including the blues. The blues progression has a distinctive form in lyrics and phrase and chord structure and duration. It is, at its most basic, based on the I-IV-V chords of a key.
The blues can be played in any key, but guitar and bass players prefer open chords, that is, chords with several open strings: E-A-B7 or A-D-E7. Keyboardists may prefer chords with fewer black keys, such as C-F-G7 or G-C-D7. The blues progression, in C, is as follows: