Free Comic Book Day, abbreviated as FCBD, is an annual promotional effort by the North American comic book industry designed to help bring new readers into independent comic book stores. It is held on the first Saturday in May every year.
For the event, major publishers release special standalone comics to tie in to one or more of their currently-ongoing titles, effectively acting as a free sampler for what their series has to offer.
Titan Comics began releasing special Doctor Who comic issues for the event in 2015, and continued to do so until 2019. All issues released have contained new comic stories tying into their various ongoing Doctor Who titles.
IDW Publishing have also been taking part in the event since its inception. Unlike Titan, however, they did not release any Doctor Who-related content for the event during their time with the license.