A BROKERED CONVENTION is when delegates do not come up with a prez nominee on the first round of voting. Then what happens?

That's when they start trading off, bargaining, bartering. That's when SUPERDELEGATES become very precious. SUPERDELEGATES are free to support whomever they choose whereas pledged delegates are not. So it could get very dicey and heated if the Dems don't have a clear candidate. Messy. Fractious. Republican conventions are never brokered because they are always in line OR ELSE? Or not?