For Software Development Project in Scrum / Kanban a card / user story is done when the customer accepts it but before that, the ScrumMaster should mark the card done when the QA is done. The QA lead should mark the card done when all (User Acceptance Tests) is done for the card. This chain continues in reverse order till the point of requirement gathering. The definition of DONE should accumulate all the points in the entire life cycle as a checklist for DONE. In certain cases, teams get excited and miss critical aspects / requirements due to the fast paced development cycle. Such checklist or definition of DONE helps to keep things on track and ensure that the team doesn't miss anything.
Every organization follows different processes and hence the cards / user stories will have a different life cycle in different organization. So every business or project will have a different definition of DONE. The important aspect is to define the DONE and understand the importance of it.
The definition of DONE in agile should also be aimed at becoming lean and not adding unnecessary checklist or tasks in the card / user story. Most of the organizations have additional tasks attached to card / user story like documentation. I am not against documentation but such tasks should be reviewed and should help in going lean.
On closing notes I would advise teams to start with adding Customer Acceptance to the definition of DONE and start adding tasks required for achieving Customer Acceptance. The definition of DONE should enable error free Customer Acceptance and going lean.
