The Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product. The Definition of Done is created by the Scrum Team, not just the Developers. The Scrum Team must have a shared understanding of what it means for work to be complete, to ensure transparency. The Definition of Done is used to assess when work is complete on the product Increment. The Definition of Done may vary significantly per Scrum Team, depending on the context. The Definition of Done evolves over time and is updated whenever the Scrum Team learns more about the product and the environment in which it operates.
References:
* The Scrum Guide
* Understanding and Applying the Scrum Framework
* Professional Scrum Product Owner™ I Certification