This term refers to the excahnge of looks that takes place in cinema but it was not until the 1970s that it was written about and theorised. In the early 1970s, first French and then British and American film theorists began applying psychoanalysis to film in an attempt to discuss the spectator/screen relationship as well as the textual relationships within the film.
Drawing in particular on Freud's theory of libido drives and Lacan's theory of the mirror stage, they sought to explain how cinema works at the level of the unconscious. Indeed, they maintained that the processes of the cinema mimics the workings of the unconscious.
The spectator sits in a darkened room, desiring to look at the screen and deriving visual pleasure from what he or she sees. Part of that pleasure is also derived from the narcissistic identification she or he feels with the person on the screen. But there is more; the spectator also has the illusion of controlling that image.
First, because the Renaissance perspective which the cinematic image provides ensures that the spectator is subject of the gaze; and second, given that the projector is positioned behind the spectator's head, this means that the it is as if those images are the spectator's own imaginings on screen.
Feminists took up this concept of the gaze and submitted it to more rigorous analysis. Laura Mulvey's vital and deliberately-polemical article, Visual Pleasure and Narrative Cinema (1975) started the debate by demonstrating the domination of the male gaze, within and without the screen, at the expense of the woman's; so much so that the female spectator had little to do, gaze upon or identify with.
The exchange or relay of looks, (as it is also known) within film reproduces the voyeuristic pleasure of the cinematic apparatus but only for the male. In fact, given that woman is normally, both within the film and on screen, the prime object that is being looked at, (and thus controlled) much feminist film theory has argued that the gaze is male through and through. It has thus been held that by attempting to expose how woman is constructed cinematically as an object of the male gaze, it is possible to deconstruct the normalising or naturalising process of patriarchal (male) socialisation.