Chas is right. As much as anything, jazz is an ATTITUDE...an approach to free-form, but complex structure. It's trading ideas and playing off of each other extemporaneously.
Sometimes, there will be a unique joint effort(players and listeners) to take a tune in an entirely different direction.
In those rare, magic moments, the high is unbelieveable.
To understand you have to experience it.
And once you do, it's a life-changer...something you never forget.
And those moments are, for me at least, what makes it all worthwhile.
Russ