Breach of contract is a legal concept in which a binding agreement or bargained-for exchange is not honored by one of the parties to the contract by non-performance or interference with the other party's performance.

A breach may be a minor one (also called a partial breach or an immaterial breach), in which case the non-breaching party will not be entitled to non-performance of its obligations, but only to damages.

A material breach is a breach so fundamental that it excuses the aggrieved party from further performance and entitles that party to sue for damages.

An anticipatory breach is an unequivocal indication that the party will not perform when performance is due. An anticipatory breach gives the non-breaching party the option to treat such a repudiation as an immediate breach and sue for damages.