What is "Trim"?

Coach Chris and Coach Ev are talking all about trim, and it's one of those topics thats tough to discuss because its so subtly pervasive in surfing, but mostly only discussed as it pertains to how you ride a wave. Well your favorite coaches are here to let you know that trim is an ever present concept and the more aware of it you are, the more sensitive of a surfer you can train yourself to be.