Establishing an upfront, common understanding of “done” that suits the unique dynamics of each development project can be one of the most critical activities for Agile teams and the first one !
With a consistent meaning of done, agreed to by the whole team, velocity or throughput becomes more stable – allowing your team to make and meet commitments, establish priorities and plan iterations.
Some ressources :
Official https://www.scrum.org/Resources/Scrum-Glossary/Definition-of-Done
Large vision http://gettingresults.com/wiki/Explained_-_Agile_Results_in_a_Nutshell
