OK, confessions time. Having a weird schooling of rock, then jazz, then classical theory, no one ever told me what a vamp is and most of the definitions I can find through google are 'an improvised musical accompaniment' (yeah, thanks

) so can someone help me out?
Also, what are Coltrane changes? I've never really studied what he is doing. I guess I've never really paid much attention to 'formal' playing and just pinched the stuff I wanted at the time which in some ways is good, but also means there are lots of gaps in my theory.