Filming & Production
Close-up
Also called: CU, close up shot
In classic shot sizing a close-up frames head and shoulders. The extreme close-up goes tighter, onto eyes or hands. On a product or a control it is the shot that shows the thing you are describing instead of gesturing at it.
Cutting in tighter raises intensity, and that is the reason talking-head editors punch in on the important line. Used constantly it flattens out. If every shot is a close-up then the tight one has nothing left to escalate to, so film a wider option on the same take and give the edit somewhere to cut from.