What is Data-quality rule, data contract?

A data-quality rule is an automated check of a dataset against an expectation — that it is complete, that its values are valid, that it is consistent with itself and with other sources, that it is timely — run every time the data are produced, with a severity and an owner who acts on its failures. A data contract is the agreement between a dataset’s producer and its consumers that states its schema, its rules and its delivery times, so that a change on either side is a change to the contract rather than a surprise.