The Definition of Done is the Increment's commitment, meaning a shared and explicit standard
for the state work must reach before anyone calls it finished. Its job is to make
"done" mean the same thing to every person on the team, on every item, every time.
Why it is a commitment rather than a checklist
Framing it as a commitment rather than a process artifact is the 2020 Guide being
precise. A checklist is something you tick; a commitment is something the Increment
must satisfy before it exists at all. An item that misses it does not become a
smaller Increment. It goes back to the Product Backlog.
Who owns it
If the organisation has a standard, it is the floor. The Scrum Team follows it and may tighten it. If there is no organisational standard, the Scrum Team creates one.
Notice who is absent from both sentences, no single accountability owns the
Definition of Done, which is exactly what the exam is checking when it offers you
"the Product Owner" or "the Scrum Master" as an answer.
Multiple teams, one product
Where several Scrum Teams work on the same product, they share one Definition of
Done. Anything else produces Increments that cannot be integrated, which defeats
the point of having an Increment at all.
Common misconceptions
“The Product Owner decides the Definition of Done.”
If it is not an organisational standard, the Scrum Team must create one appropriate for the product. Where the organisation supplies one, the team must follow it as a minimum and may make it stricter, never looser.
“Work that is nearly done can still be shown at the Sprint Review.”
An item that does not meet the Definition of Done returns to the Product Backlog. Presenting undone work leaves the remaining effort untracked.
“Each Developer can hold their own idea of Done.”
It is a single shared standard. Multiple Scrum Teams on one product share one Definition of Done, because they produce one Increment between them.
2 questions test this concept
A Product Owner asks whether an item that is code complete but not yet security reviewed can be shown at the Sprint Review, given that the Definition of Done includes a security review. What is the correct position?
AIt may be shown as long as the remaining work is disclosed to stakeholders.
BIt is not Done, so it cannot be released or presented at the Sprint Review, and it returns to the Product Backlog for future consideration.
CThe Product Owner may waive the Definition of Done for a single item if the value is high enough.
DIt counts as Done because the Definition of Done is a guideline rather than a rule.