A common fictional concept is that the characters are unaware of the fact that they're in a story. This is the FourthWall: the glass on the front of the TV tube, the invisible wall at the front of the stage play set.

This separation between the characters and the audience helps to preserve WillingSuspensionOfDisbelief: When the fictional characters act like their story is RealLife, it's easier for the audience to treat it the same way.

See ThreeWallSet for the production implications of this concept. TheCouch often faces the FourthWall.

Straight uses of this trope are too numerous to list and a lot less interesting than BreakingTheFourthWall or when there is NoFourthWall. The exploration and subversion of the FourthWall is a common trait of PostModernism.

See also SlidingScaleOfFourthWallHardness
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