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.

The term that describes a duty that is enforced by a court and where non-fulfilment may incur a penalty.

A violation of a statute, regulation or ordinance, which may be criminal or merely not in conformity; that which lacks authority of or support from the law.