Box set (theatre)

In theatre, a box set is a set with a proscenium arch stage and three walls. The proscenium opening is the fourth wall. Box sets create the illusion of an interior room on the stage, and are contrasted with earlier forms of sets in which sliding flats with gaps between them created an illusion of perspective.

Box sets were introduced to the English theatre by Elizabeth Vestris. They were popularized by Marie Wilton at the Prince of Wales's Royal Theater. They later became a feature of realist theatre, and an example of the "fourth wall removed" principle that characterized the work of noted realists such as Henrik Ibsen, Émile Zola, George Bernard Shaw, and Anton Chekhov.

In play style of Realism, the Box Set of the stage was a room with either plain black backdrop or three walls, the fourth wall was invisible, separating the characters from the audience, the ceiling was tilted down at the far end of the stage and up toward the audience. Doors slammed instead of swinging when being shut just like in a real world.

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