A contract is an agreement that is legally enforceable. For a contract to be valid, it requires:
1) Competent parties that agree through mutual offer and acceptance.
2) Consideration, which is a promise or set of promises. Total absence of consideration renders a contract unenforceable, with some exceptions.
3) The consideration cannot be unlawful, against public policy, or involve a wager.
4) Other requirements include not being in restraint of marriage, trade, or legal proceedings. The contract must also not be uncertain, impossible, or involve fraud, coercion, or mistake by both parties.