A lesson learned is a knowledge or understanding gained by experience. The experience may be positive, as in a successful task/ project or negative, as in a mishap or failure. A lesson must be significant in that it has a real or assumed impact on operations; valid in that is factually and technically correct; and applicable in that it identifies a specific design, process, or decision that reduces or eliminates the potential for failures and mishaps, or reinforces a positive result. This definition implies a set of requirements for lessons specified through the phrases knowledge, experience, impact on operations, technically correct, and applicable.
