12 Bar Blues is a pattern of chords which repeats every 12 bars. There are hundreds of wellknown songs based on this chord progression, i.e., they contain basically the same chords in the same order. 12 bar blues is commonly used in rock music.
Some well known songs which use this 12 bar chord pattern are:
Play the following 12 bar blues, in the key of C major, which uses some of the chords you have learnt so far. When a song is said to be in the key of C major, it means that the most important chord (and usually the first chord) is the C chord, and that the notes of the melody of the song are from the C major scale.
To finish a 12 bar blues, press the ending button, (as on the recording), or play one bar of the opening chord (in this case a C chord), and press the stop button.
This pattern of chords will probably sound familiar to you.
On the recording there are two bars introduction to this song.