In matters of personal defense, we often speak of the OODA Loop. Of course, the OODA Loop has applicability to life in general, but for many people the first time they hear about it is in some class teaching personal defense.
BTW, while it’s common to refer to it as the “oo-dah loop”, Massad Ayoob made it clear back in my MAG-20 class that the creator of the OODA Loop – John Boyd – referred to it as the “Oh-Oh-Dee-Ay Loop”.
Pronunciation aside, The Art of Manliness wrote a rather in-depth piece on the OODA Loop. If you’re unfamiliar with the concept, or know about it but appreciate some deeper knowledge of a topic, give it a read.