What is the term for the imaginary wall through which the audience views the play?

The term "Fourth Wall" refers to the imaginary barrier that separates the audience from the actors on stage. This concept originates from the idea of a stage having three physical walls and an invisible fourth wall that allows the audience to observe the action of the play while remaining separate from it. This term is fundamental in theatre, as it describes the audience's perspective and their engagement with the performance without breaking the reality that the actors are creating.

When this wall is acknowledged or broken, it can create a different kind of interaction, such as characters speaking directly to the audience or acknowledging the act of performing. Understanding the fourth wall is crucial for theatrical conventions and the ways in which different theatrical styles engage with the audience, such as realism and avant-garde theatre, which might choose to ignore this boundary for dramatic effect.