1.The purpose of the main light it is the principal source of light in a photograph, particularly in a studio setup, casting the dominant shadows and defining the texture and volume of the subject.

2. The purpose of the fill light is to fill in the shadows created by the main light. The fill light is often positioned opposite of the main or key light, filling in the shadow side of the subject or object.

3. Butterfly lighting, Split, 3/4, and rembrant.