Acceptance criteria are specific and measurable conditions that a product or service must meet to be considered satisfactory and accepted by the customer or end-user. They serve as a way to define the requirements of a project or deliverable in a clear and concise manner, and help to ensure that everyone involved understands what is expected and what will be delivered.

Acceptance criteria are typically created during the planning phase of a project or sprint, and are based on the user stories or requirements that have been defined. They should be written in a way that is unambiguous and testable, so that they can be used as the basis for acceptance testing.