Closing a project is a distinct phase, not an afterthought: it includes confirming all deliverables were accepted by the client or sponsor, releasing team members and resources, settling final invoices or payments, and formally documenting that the project is complete. A lessons-learned session, sometimes called a retrospective, brings the team together to discuss what went well, what didn't, and what should change next time -- the value comes only if the findings are written down and actually referenced on the next project, not just discussed once and forgotten. Archiving documentation (the scope statement, schedule, risk register, budget, and final report) in an organized, accessible location means future projects don't have to reinvent estimates or repeat the same mistakes. Skipping formal closure is a common mistake that leaves loose ends, unbilled work, and no organizational memory for next time.