| Type | Media concept |
| Media | Literature • Film • Television • Video games |
| Origin | Various sources |
| Examples | Frasier (TV series) • Better Call Saul • Metal Gear Solid: Peace Walker |
| Significance | Expanding original content • Appealing to niche audiences • Providing alternate perspectives |
| Characteristics | Branching ideas • Diverging storylines • Connections to main premise |
