Having no legal force or binding effect; unable in law to support the purpose for which it was intended. If a contract is null and void from the beginning because it seriously offends the law or public policy it is said to be void ab initio.

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.