Rhythm changes, also know is the I, vi, ii, V chord progression, is the most common chord progression used in jazz music. Countless jazz songs, as well as pop songs, use this chord progression. The name comes from the George Gershwin song I’ve Got Rhythm, which has become a jazz standard in The Great American Song Book. During the early days of jazz, when musicians where jamming, or learning a tune, they would explain this song is just like I’ve Got Rhythm. Then, to save words I suppose, they began calling the chord progression rhythm changes.