Observe, Orient, Decide, Act
The OODA loop is a decision-making cycle developed by Air Force Colonel John Boyd: observe the situation, orient by interpreting what it means, decide on a course of action, and act. Security teams apply it to incident response and threat hunting, where the side that cycles through the loop faster gains the advantage. It matters because defense is a contest of speed, and getting inside the attacker's loop lets defenders disrupt an intrusion before it succeeds.