The Arrowverse is an American superhero media franchise and shared universe that is centered on various interconnected television series based on DC Comics superhero characters, primarily airing on The CW as well as web series on CW Seed. The series were developed by Greg Berlanti, Marc Guggenheim, Andrew Kreisberg, Geoff Johns, Ali Adler, Phil Klemmer, Salim Akil, and Caroline Dries. Set in a shared fictional multiverse much like the DC Universe and DC Multiverse in comic books, it was established by crossing over common plot elements, settings, cast and characters that span six live-action television series and two animated series.
Promotional image for the 2016–17 television season
A shared universe or shared world is a fictional universe from a set of creative works where one or more writers independently contribute works that can stand alone but fits into the joint development of the storyline, characters, or world of the overall project. It is common in genres like science fiction. It differs from collaborative writing in which multiple artists are working together on the same work and from crossovers where the works and characters are independent except for a single meeting.
Early example: Captain Marvel and Bulletman join forces to battle Captain Nazi, thereby establishing a shared continuity within the Fawcett "universe".