If any party fails to do anything agreed upon in a contract, what is this referred to as?

The situation described in the question pertains to a party not fulfilling their commitments as outlined in a contract, which is known as a breach of contract. A breach occurs when one party fails to complete their end of the agreement without lawful justification. This could involve not delivering goods or services, failing to pay, or not adhering to other stipulated terms. The essence of contract law is that parties have a legal obligation to perform that which they have agreed upon, and when this does not happen, the injured party has the right to seek remedies, which may include damages or specific performance.

The other terms mentioned do not accurately capture the concept. Contractual obligation refers to the duties that parties are required to fulfill within the contract; it does not describe the act of failing to meet those duties. A compromise agreement typically involves both parties settling a dispute by making mutual concessions, rather than failing to meet obligations. An amendment is a formal change or addition to the contract itself, which does not pertain to the failure to perform duties. Thus, the correct answer clearly identifies the legal issue of non-performance in contract law.