Aims Debriefing is a fundamental part of simulation training in health care, but remains a complex and difficult process to put in place. The aim of this article is to define the postsimulation debriefing, to clarify objectives and identify the main principles of debriefing with regard to the current literature. Results Several definitions of postsimulation debriefing exist in the literature, and have in common the reflexive practice with respect to action performed by the participants. This guided or facilitated analysis is carried out in a context of social interaction within an experiential learning cycle. The purpose of debriefing is to understand the student’s reaction and reasoning based on observations (from actions and results of the simulation), so as to validate or rebuild them. Debriefing is typically carried out in three phases: reaction–description, analysis, and summary–transposition, all of which need to be adapted to account for multiple variables. In 2011, Raemer et al. proposed that a debriefing takes place using the 5 “W” principles: Who, What, When, Where, and Why, which forms the basis of our analysis. Conclusion Debriefing is one of the principal parts of a fullscale medical simulation. It is a complex multiple-level process. The completion of a debriefing remains a difficult exercise for trainers. Beyond the broad principles discussed in this article, many questions remain unanswered.