Colonel John Boyd coined a concept he called the O.O.D.A. Loop (he apparently always said each letter as opposed to calling the oo-dah loop), a simple way of looking at a conflict (typically physical).
The letters in the acronym stand for:
The basic idea being that first an action must be observed (a punch is coming at my face), what is observed must be oriented toward (I should do something about this), then a course of action must be decided on (inward block and move to the outside of the arm), the decided up action must be taken.
Yeah this is a really drawn out example and if your training is at a sufficient level you’ll move from observing to acting without any conscious thought – this is an example of fast transience – transitioning from one stage in the loop to the next as fast as possible.
The basic theory is that if you are able to move from Observation to Action faster than an opponent can, you’ll be victorious – basically you “get inside” of their loop by transitioning faster and re/claiming the initiative in the situation and thus make the opponent react to you.