What exactly is the definition of a rythym change.

[jazzharbinger07]

O.K. call me what you want, but I've heard it over and over ..had on idea of what it is..but I need to know for a fact. thanks for your help. JH07

[hglord]

"Rhythm changes" are the chord changes to George Gershwin's song "I Got Rhythm." These chord changes are I VI II V. In the key of C major that's CMaj7 Am7 Dm7 G7. Gershwin was not the first to use these chord changes; there are many, many songs based on them including "Heart And Soul," "Side by Side," "These Foolish Things," "It's Only a Paper Moon," and hundreds of others. Musicians like these changes because they are easy and lend themselves to many variations.

I'm sure that some people will insist that "real" rhythm changes include the bridge to "I Got Rhythm" which is a simple circle of fifths, but in my experience, when the phrase "rhythm changes" is used by musicians to describe a tune, most people are referring to the I VI II V changes, not the bridge.

[jazzy mary]

But, what did people do before Gershwin wrote "I Got Rythmn". Where did he get it from? And why that song?

[JazzAt52ndStreet]

obviously not exclusivly.....I IV V...from the blues tradition.

....More simply, "Rhythm Changes" is a less korny name for the Gershwin song "I Got Rhythm". And "I Got Rhythm" happens to have the things that Hglord described.

-52nd

[Nate Dorward]

It's not EXACTLY the changes to the Gershwin tune--it's an abstraction of them, minus a few bars at the end (the original isn't 32 bars long).

& the B section is not optional! Though there are several variations on it (e.g. the "Eternal Triangle" changes).