Three-point Lighting
The standard setup of key, fill and rim lights that models a subject and separates it from the background.
In depth
Inherited from cinema and theatre, three-point lighting is a starting grammar rather than a rule: the key gives form, the fill controls how deep the shadows go, and the rim gives depth. Learning it well means learning when to remove a light, since many of the strongest portraits use only a key and a reflector.
Examples in practice
An interview setup places a softbox key camera-left, a bounce fill camera-right and a small rim light behind the subject's shoulder.