Definition:
An After Action Review (AAR) is a simple process used by a team to capture the lessons learned from past successes and failures, with the goal of improving future performance. It is an opportunity for a team to reflect on a project, activity, event or task so that they can do better the next time. It can also be employed in the course of a project to learn while doing. AARs should be carried out with an open spirit and no intent to blame. The American Army used the phrase “leave your rank at the door” to optimize learning in this process. Some groups document the review results; others prefer to emphasize the no-blame culture by having no written record.
Further Reading:
Book: Disciplined Agile Delivery by Scott Ambler and Mark Lines.