Watch the Playing a 12 Bar Blues online guitar lesson by Susan Mazer from Hands-On Guitar: The Beginner's Guide

Now we’re going to apply these chords to what’s called a twelve-bar blues. This means that there are 12 measures (sometimes called a bar) in our form. We’ll keep repeating the same 12 measures over and over. Again, if you look at the list of tunes you’ll see that this form is used in all styles of music.