Free Comic Book Day (FCBD) is an annual promotional effort by the North American comic book industry to attract new readers to independent comic book stores. It usually takes place on the first Saturday of May and is often cross-promoted with the release of a superhero film. Over two thousand participating stores give away millions of comic books annually. The event was proposed by Joe Field in the August 2001 issue of Comics & Games Retailer magazine and Free Comic Book Day was launched in 2002, coordinated by the industry’s single large distributor, Diamond Comic Distributors. FCBD has become an official Children’s Book Week event and has inspired similar events for German- and Dutch-language comics industries.

https://en.wikipedia.org/wiki/Free_Comic_Book_Day