A chord progression is sequence of chords that defines the harmony of a song. A chord is a few notes played simultaneously. Think of a guy strumming a guitar, h

A chord progression is sequence of chords that defines the harmony of a song. A chord is a few notes played simultaneously. Think of a guy strumming a guitar, he would play the harmony with his guitar, and sing the melody. In western music, chords and chord progressions are constructed according to certain rules (google "harmonization of the major scale") that are now familiar to most listeners. Actually, many pop songs share exactly the same sequence of chords. This contrats with jazz which tends to bend the rules.