The Blues is based on a simple pattern. "The blues are easy to play but hard to feel" - Jimi Hendrix. A common form for the blues is a repeating form of 12 bars (each bar has 4 beats). This is compiled into 3 phrases or sections, each 4 bars long. Basic blues only requires 3 chords, one based on the first note in the scale - the tonic chord, one based on the fourth note in the scale - the subdominant chord, and one based on the fifth note in the scale - the dominant chord. The first 4 bar section or phrase uses only the tonic chord. A common variation is the use of the subdominant chord in the second bar. The second phrase has 2 bars (8 beats) of subdominant chord, then 2 bars of tonic chord. The third phrase has 1 bar (4 beats) dominant chord, 1 bar subdominant chord and ends with 2 bars tonic chord.