Offer and Acceptance define contract formation; definitions clarify promisor, promisee, consideration and enforceability consequences under statute. Definitions governing contract formation and enforceability: a proposal (offer) is a willingness to act or abstain to obtain assent; acceptance converts a proposal into a promise; the parties are promisor and promisee; consideration consists of acts, abstentions, or promises done at the promisor's desire; reciprocal promises and exchanged promises constitute an agreement. An unenforceable agreement is void; an enforceable agreement is a contract; an agreement enforceable only at one party's option is voidable; a contract ceases to be enforceable and becomes void when enforceability ends.