Superimposing a person's face onto a photo or video. For years, countless images of nude celebrities have actually been the heads of famous people superimposed onto photos of other people's bodies. Face swapping is also performed on videos, and the same facial expressions, eye and mouth movements of the source are carried over to the target. Face "reenactment" techniques can even alter the target's expression when necessary to emphasize a point. Adding voice is not difficult as realistic audio simulations have been around for decades.
Face swap has amazing potential for making movies and commercials, as faces of people who cannot perform sufficiently can be applied to actors who can. In addition, busy celebrities can license their faces while others do the acting. However, when face swap is done without the permission of the superimposed person, there may be serious consequences (see deepfake