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):
- Aside Glance: Someone looks in the direction of the screen, doesn't say anything, and doesn't get acknowledged.
- Audience? What Audience?: Someone mentions something that implies the work is fictional (like writers, an audience, etc) and another person is just confused.
- Breaking the Fourth Wall: Talking to the audience.
- Breaking the Reviewer's Wall: Reviewers interacting with the work's characters.
- Camera Abuse: Something affects the camera so that the screen will appear wonky.
- End-of-Series Awareness: A character is aware they're fictional and that their work is ending.
- Exploiting the Fourth Wall: Using the fourth wall for practical reasons.
- Found Footage Films: Putting the camera on the character's side of the fourth wall.
- Fourth-Wall Mail Slot: Fictional characters answer questions from the viewers/readers/etc.
- Fourth Wall Myopia: Where fans forget that fictional people won't know as much as their watchers do.
- Fourth-Wall Observer: One person is aware the work is fictional.
- Fourth Wall Portrait: In a work with cartoony-looking people, someone thinks a realistic drawing of a person looks crazy.
- Fourth Wall Psych: The fourth wall appears to be broken but isn't really.
- Fourth Wall Shut In Story: An author gets trapped in their own work.
- The Fourth Wall Will Not Protect You: The villain acts like they're going to hurt/kill/etc the viewers.
- Frame Break: Breaking through (or even just hitting) the frame of the panel.
- From Beyond the Fourth Wall: Someone in a work gets items from the author or us.
- Leaning on the Fourth Wall: Implying the fourth wall or saying things like "If this were a movie".
- Logging onto the Fourth Wall: Fictional websites.
- Medium Awareness: Being aware you're fictional.
- Ninja Prop: Props that should've been beyond the fourth wall suddenly affects the world in some way.
- No Fourth Wall: Everybody is well aware they're fictional characters.
- No Inner Fourth Wall: Characters in a Show Within a Show break the fourth wall.
- Noticing the Fourth Wall: Characters suddenly realise they're fictional.
- Painting the Medium: Some part of the fiction is stylized to convey an information for the audience; this stylizing won't be noticeable to the fictional characters themselves.
- The Player Is the Most Important Resource: Video game characters state that they need the players.
- Reading Ahead in the Script: The characters predict the future by reading their script.
- Refugee from TV Land: Someone goes through the fourth wall and enters the land of reality.
- Scolding the Fourth Wall Breaker: A character scolds another character in-universe for breaking the fourth wall.
- Screen Tap: Tapping the screen.
- Sliding Scale of Fourth Wall Hardness
- This Is Reality: Characters think they're real people.
- Trapped in TV Land: Someone goes through the fourth wall and enters the land of fiction.