I'm sure this has been posted somewhere before, but I couldn't find the answer to my exact question.
Basically, it's probably a bit late now as I've already been to two conferences... but I have always just submitted an abstract, turned up and given my presentation and never given it another thought.
Anyway, someone else in my group has just published a paper in the conference proceedings following presenting a poster and it got me thinking...

Was I supposed to have done that too?? I've never been asked to submit a full paper before the conference, but the abstract book has said to drop off the paper at the registration desk. Which I just ignored, assuming that I would publish in a peer-reviewed journal later.
Is it "compulsory" to submit a full paper? Obviously, the world hasn't ground to a halt since I haven't, but what does this mean for me since I never submitted them?
I assumed it was just optional for anyone who wanted to get another publication, but I was worried about copyright and publishing future articles on the same work so never did.