Acceptance criteria represents specific and defined list of conditions that must be met before a project has been considered completed and the project deliverables can and will be accepted by the assigning party. Customarily the acceptance criteria should be outlined in specific detail before work on the project has commenced and a very careful timeline should be set forth to make sure that all parties are onboard. Acceptance criteria can represent certain essential requirements that must be met within the final deliverables themselves, or specific conditions that must be met during the process in which those deliverables are assembled and completed. In providing a series of acceptance criteria to the assignee, the assigning party should when possible prioritize the acceptance criteria. In the event that a series of acceptance criteria is not met, or is met only partially, the final set of deliverables can either be refused for acceptance outright or, in some cases, it may be assigned the status of conditional acceptance, that being, an acceptance pending modification or correction to better meet the acceptance criteria.
This term is defined in the 3rd and the 4th edition of the PMBOK.