A binding magical contract is a natural, magically-enforced agreement between two or more wizards or witches who partake in it. Putting a name in the Goblet of Fire formed such a contract. Those whose names were selected were obligated to compete in the Triwizard Tournament. Harry Potter apparently thought that he would be bound as a party to this contract, and he participated in the 1994 Tournament, despite the fact that his name was entered by someone other than himself. However, since he did not try to refuse to participate, he did not find out whether he was required by contract to participate.