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 demonstration of the willingness of a party to enter into a bargain, made in such a way that another individual is justified in understanding that his or her assent to the bargain is invited and that such assent will conclude the bargain. The general rule is that it must be reasonable in the circumstances for the recipient to believe that the communication is an offer. The more definite the communication, the more likely it will constitute an offer.

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.

Sometimes known as a repudiatory breach, is a breach of an essential part of a contract that it permits the distressed party to terminate performance of the contract, in addition to entitling that party to sue for damages.

A breach of contract that is so fundamental that it permits the injured party to terminate the performance of the contract, in addition to entitling that party to sue for damages.

Significant enough substantial failure in the performance of a contract, as to give the affected party the right to sue for damages as well as release the aggrieved party from its obligations.