Genres
Fictional universe
An internally consistent fictional setting, also called an imagined or constructed universe, in which narrative works take place.
A fictional universe, also known as an imagined universe, constructed universe or diegetic world, is an internally consistent fictional setting used in a narrative work or work of art. The concept is most associated with fantasy and science fiction: a universe may bear little apparent connection to the real world, as in the remote galaxy of Star Wars, or be a heavily fictionalized version of Earth, as in The Lord of the Rings. Boundaries matter at series scale: under Don Markstein's rule, if characters A and B have met, and B and C have met, then A and C share a universe, and some universes, such as Niven's Known Space, are opened to multiple authors with roughly equal canonical status.
For novel and web-serial writers this is the container worldbuilding produces: every established fact, from the map to the myths of a legendarium, becomes canon that every later chapter must respect. A shared universe is the multi-author version of that same discipline.