A silhouette features a highly underexposed subject with a lot more light behind it than in front of it. The background may be overexposed or normally exposed, as long as the subject is greatly underexposed.

The simplest way to create a silhouette is to place the subject indoors, in an open doorway or window. Auto exposure will read the bright background and expose for it, rather than the subject. This will also happen with a hand-held light meter if you don't take the contrast into consideration.