A shared universe or shared world is a fictional universe from a set of creative works where one or more writers (or other artists) 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. The term shared universe is also used within comics to reflect the overall milieu created by the comic book publisher in which characters, events, and premises from one product line appear in other product lines in a media franchise. A specific kind of shared universe that is published across a variety of media (such as novels and films), each of them contributing to the growth, history, and status of the setting is called an "imaginary entertainment environment."The term has also been used in a wider, non-literary sense to convey interdisciplinary or social commonality, often in the context of a "shared universe of discourse". Source: Wikipedia (en)