Wikipedia Reference Information
The fourth wall is the imaginary invisible wall at the front of the stage in a proscenium theater, through which the audience sees the action in the world of the play. The concept is generally presumed to have originated in nineteenth century theatre with the advent of theatrical realism.
Although it originated in theatre, where conventional three-walled stage sets provide a more literal "fourth wall", the term has been adopted by other media, such as cinema, television, and literature, to more generally refer to the boundary between the fiction and the audience.
The fourth wall is part of the suspension of disbelief between a fictional work and an audience. The audience will usually passively accept the presence of the fourth wall without giving it any direct thought, allowing them to enjoy the fiction as if they were observing real events. The presence of a fourth wall is one of the best established conventions of fiction and as such has led some artists to draw direct attention to it for dramatic effect. For instance, in A.R. Gurney's The Fourth Wall, a quartet of characters deal with housewife Peggy's obsession with a blank wall in her house, slowly being drawn into a series of theatre clichés as the furniture and action on the stage become more and more directed to the supposed fourth wall.
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