Basic 3-point lighting

 Key light

The key light is the main light source it is used to highlight the form and dimension of the subject. there are two types of key light high key and low key.

High key lighting is where the subject is extremely bright with more fill lighting and shadow are kept softer.

Low key lighting is where the subject is minimum exposure to the light with less fill lighting and the shadow is increased and kept sharp to boost the dark tones and contrast.

Fill light

Fill light is a supportive light that doesn't change the character of the main light and is used to soften shadows. It is mostly used from the opposing direction of the main light.

Backlight

Backlight is used to create separation of the object from its illuminate background it is done by using the lighting instrument to create a glow effect on the edges of the subject to make a sense of depth in the scene.