Breaking the fourth wall is a performance convention in which an imaginary wall separates actors from the audience, and the actors act as if they cannot see through this wall. Breaking the fourth wall means doing or saying something that either explicitly or implicitly acknowledges the artificiality of the environment and the fact that both the presenters and audience are aware of that artificiality. This term comes from the theatre, where the three surrounding walls enclose the stage while an invisible “4th wall” is left out for the sake of the viewer. Breaking the fourth wall is a device used in many contexts, including theater, film, television, literature, and video games.

Breaking the fourth wall can be used for comedic effect, as seen in Looney Tunes, Monty Pythons Flying Circus, and other comedy-based programs. It can also be used to draw attention to or invite reflection about a specific in-universe issue, as seen in the first episode of the final season of the show Attack on Titan. Breaking the fourth wall can benefit a scene by checking in with the viewer during moments of high impact.

In literature, breaking the fourth wall is a metalepsis, which is a technique often used in metafiction. The metafiction genre occurs when a character within a literary work acknowledges the reality that they are in fact a fictitious being. The use of the fourth wall in literature can be traced back as far as The Canterbury Tales and Don Quixote.

Overall, breaking the fourth wall is a technique that can be used to enhance storytelling and engage the audience in a unique way.