The Marvel Cinematic Universe (MCU) is a media franchise and shared universe centered around a series of superhero films and television series produced by Marvel Studios. It is based on characters from American comic books published by Marvel Comics. The MCU began with the release of Iron Man in 2008 and has since expanded to include numerous films and shows featuring iconic characters like Captain America, Thor, and Spider-Man. The franchise is divided into phases, with each phase introducing new characters and storylines while connecting to a larger narrative. The MCU has become one of the highest-grossing film franchises in history, known for its interconnected storytelling and crossover events, such as The Avengers films.