What is the 'Rhythm Changes' progression?

[bernie01]

I was at a party on Sat. night where a jazz jam was happening and talking to the bass player he mentioned the 'Rhythm Changes'. Well, we'd had a few beers so I didn't really grasp what he was talking about, so I've been searching the web and see people referring to it as a common jazz chord progression like ii/V/I etc. (at least I think so...)
So can someone explain what this progression is? Or point me to a URL that explains it?
Thanks, Bernie.
[edit]
Whoa! Just changed my Google search argument slightly and found a whole lot of references to this! I get it now, the 'rhythm' part is a reference to a song title, nothing to do with rhythm!
This one points to a whole lot of others:
http://www.angelfire.com/fl4/moneych...hmchanges.html

Cool, not only did you answer your own question, but you came up with a great link to lots of other good links as well. So... thanks! :-)

Lots of folks find rhythm changes intimidating and/or baffling at first, especially because so often they're played at fast-to-very-fast tempos. But after you've played some of the tunes for awhile, you'll find you internalize the changes in the same way you likely already have with blues changes. So you don't really have to think about where you are every second; like any other tune than you already know inside and out, you just feel it and play. That's the goal, at least. ;-) And rhythm changes are fun to explore because they offer so many ready substitution possibilities, which makes it easier to play multiple choruses without repeating the same ideas over and over again.

Enjoy, and thanks again for the links. :-) CS

[Big Tony]

That was a useful collection of links, very interesting stuff. Thanks, bernie01!