When a party fails to fulfill a contract for selling goods internationally, the other party can end the contract. This is called a fundamental breach of contract. The Vienna Convention on Contracts for the International Sale of Goods sets criteria for what qualifies as a fundamental breach: the breach must be serious, result in significant harm to the other party, and not have been foreseen. This concept helps determine when a contract can be terminated due to non-performance. The Convention's approach provides clear standards for evaluating breaches, making it easier for parties to know when they can end a contract.