Definition of Done in Scrum: rules for the PMP exam
The Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product. Work that does not meet it is not part of an Increment: it cannot be released or presented at the Sprint Review, and it goes back to the Product Backlog.
What it does
The moment a Product Backlog item meets the Definition of Done, an Increment is born. The Definition gives everyone a shared understanding of what was completed. It is the commitment attached to the Increment, in the way the Product Goal belongs to the Product Backlog and the Sprint Goal to the Sprint Backlog.
If the organization has a Definition of Done as a standard, every Scrum Team must follow it as a minimum. If not, the Scrum Team creates one suited to the product. The Developers must conform to it.
Several teams, one Definition
When multiple Scrum Teams work on the same product, they must mutually define and comply with the same Definition of Done. A newer team cannot keep a lighter Definition because its components seem less risky.
Work that is not Done, and work that is
Example: an item a key stakeholder has long awaited works, but has failed the performance tests the Definition of Done requires. It cannot be shown at tomorrow's Sprint Review, not even flagged as unfinished. It returns to the Product Backlog.
The reverse also holds. An Increment that meets the Definition of Done may be delivered to stakeholders before the Sprint ends. The Scrum Guide says the Sprint Review should never be considered a gate to releasing value.
The Sprint Retrospective is where the team inspects its Definition of Done. If items called finished keep reaching users with defects, that is what the team looks at.
Where the exam catches people
Believing unfinished work can be demonstrated if it is labeled as unfinished: it cannot be presented at the Sprint Review at all.
Believing each team on a product can set its own Definition of Done: teams on the same product share one.
Believing Done work must wait for the Sprint Review: an Increment may be released before the Sprint ends.
Believing the Scrum Master or Product Owner writes the Definition of Done: without an organizational standard, the Scrum Team creates it.