In portrait photography, what is 'broad' lighting? What is 'short' lighting?

Question

What are 'broad' and 'short' lighting when it comes to studio portraiture, and when should I use each?

Answer

Broad Lighting: Is when a subject is posed such that the main light is directed at the side of the face that is closest to the camera. Broad lighting can add weight to a thin face, but it does this by 'adding' roundness/thickness to the face, so it is not a good style of lighting to use with bigger subjects (or even 'normal' subjects with rounder faces.

Broad Lighting Example:

Short Lighting: Is when the subject is posed such that the main light is directed at the side of the face that is furthest away from the camera. Short lighting can help 'thin' a subject who is heavy, or who has a rounder face.

Short Lighting Example:

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