Every genre of music has its 'classic' songs, and Jazz is no different. There are certain songs which, for whatever reason, have entered the Jazz repertoire and become Jazz Standards. Of these, a small number have become widely known because of their chord progression (AKA Changes). A progression could have become famous because it was widely imitated (Rhythm Changes); or particularly complex (Coltrane Changes); or because it was a derivation of yet another well known chord progression (Bird Changes are based on the 12 Bar Blues).
It also doesn't hurt that chord progressions (and song titles) cannot be copyrighted (though melodies and lyrics can). So it is common practice to steal a song's chord progression and set it to a new melody. This is precisely what happened to the chord progression of Gershwin's I Got Rhythm - literally hundreds of songs use Rhythm Changes as their chord progression.
So having learned about the theoretical aspects of Jazz (chords, scales, improvisation, voicings), it's now time to apply what we have learned to actual songs. And what better place to start than the most widely known and commonly played songs of the Jazz Repertoire.
And after we learn some of the great Jazz chord progressions, we will move on to Jazz Reharmonization where we will learn how to take a chord progression and completely change it.
