You've made some work with your team, you've finished a project iteration or you've passed through a huge crisis. It's time to look back and to gather feedback on what you and your team has done.
Whatever you call it, agile retrospective, post-mortem, "lessons learned" meeting, or post-project review, the goal is the same: formalizing lessons learned and crafting recommendations for the future. A retrospective can be paired with a review or demo focused on getting product feedback and external opinions.

You can use these workshops to fuel an agile retrospective to continuously improve the life and the productivity of a project. The ninth Agile principle outlined that retrospective is one of the most important practices in Agile development.
"At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly."
It's important that everyone gets a chance to give their feedback and opinions in a constructive atmosphere.
Don't plan too many actions if you're not sure they will be done and effective. That's why it's important to use root-cause analysis, to define clearly the problem and to prioritize actions.
Don't hesitate to start your retrospective by reviewing the actions from the previous retrospectives. Retrospective are often structured with five explicit steps:

1. Set the stage
2. Gather data
3. Generate insights
4. Decide what to do
5. Close the retrospective

You need to have people involved in the issues discussed. There are different roles in a retrospective, the facilitator which plans the meeting and assure an open conversation. This role can be taken by managers, as they should arrange organizational changes for solutions that come out of a retrospective.