A legal document, usually in writing, giving details of a formal legally binding agreement, between two or more different people or groups. To be legally binding it must contain certain elements: it must contain an offer made by one party and accepted in its entirety by the other, it must include some form of consideration whether it be money, goods or services, and it must be properly signed by all parties to it, and dated.

A contract in which all elements of a contract are specifically stated (offer, acceptance and consideration), and the terms are set out, as compared with an implied contract in which the existence of the contract is assumed by the circumstances.

An agreement where one person promises to do something or to refrain from doing something if the other person does something, but the other person makes no promise to do or refrain from doing anything so that no enforceable obligation has been given by the other person.