A very common fictional concept is that the characters are unaware of the fact that they are characters in somebody else's work of fiction.
This separation between the characters' world and the audience is the Fourth Wall—named for the imaginary wall at the front of a stage play beyond which the actors are (usually) not supposed to cross.
It's an Omnipresent Trope, because the separation of fiction and audience helps preserve the latter's Willing Suspension of Disbelief: The fictional characters treat their story as Real Life, and audience interprets it the same way.
The exploration and subversion of the Fourth Wall is a common trait of Post Modernism.
Not to be confused with That web show done by Linkara that reviews bad comic books.
Big list of related pages (overlaps somewhat with Metafiction Demanded This Index):
- Audience? What Audience?
- Breaking the Fourth Wall
- Breaking the Reviewer's Wall
- Found Footage Films: Putting the camera on the character's side of the fourth wall.
- Fourth Wall Mail Slot
- Fourth Wall Observer
- Fourth Wall Portrait
- Fourth Wall Psych
- Fourth Wall Shut-in Story
- From Beyond the Fourth Wall
- Leaning on the Fourth Wall
- Logging Onto the Fourth Wall
- No Fourth Wall
- No Inner Fourth Wall
- Noticing the Fourth Wall
- Screen Tap
- Sliding Scale of Fourth Wall Hardness
- The Fourth Wall Will Not Protect You
- This Is Reality