Breaking a contract


If someone renews a contract for one year but wants to leave before the year is up, what can happen?
I’ve looked in other posts but I’ve seen a lot of different answers.
Some people just leave and that’s that.
Some people get fined up to $15,000.
Some people get blacklisted and/or can’t return for 1 year or 5 years…
Is there a definite answer that applies to all cases?