The Internet Movie Database has added an "F" classification to its keywords page, to identify movies featuring prominent contributions from women in front of or behind the camera.

The F-Rated tag has been added to more than 21,000 titles on IMDb, to highlight works with female stars, directors or writers. The classification was launched by a group called F-Rated, and adopted by IMDb early this year.

Although thousands of films met one of the three criteria, only a handful, including "Frozen" and "Bridget Jones's Baby," were deemed to meet the F-Rated "gold standard." Those films featured female leads, female directors and at least one female writer.

The classification system is a feminist-friendly way of highlighting women's contributions to film, on and off-screen, according to the F-Rated website. "The F-Rating is applied to films by cinemas and film festivals giving movie-goers an easily identifiable label so they can choose films that fairly represent women on screen and behind the camera," the organization says.

F-Rated called for help with an IMDb "hackathon" on Tuesday morning, to add the tag to all applicable films in the database.

The classification itself is a bit hard to find on IMDb, as it's not shown on the main landing page. Instead, users must open the site's search tool and filter for the "F Rated" keyword.

The F-Rating is partially inspired by the Bechdel test, which offers criteria for evaluating how fairly a work of fiction represents women. To pass the test, a story must include a moment in which two female characters (with names) talk to one another about any subject other than a man.

"It's so basic, but the majority of films fail the Bechdel test," F-Rated founder Holly Tarquini said, in a TED talk last November.

At least four of the films nominated for Best Picture at the Oscars, including winner "Moonlight," failed the test, according to Other popular films such as the original "Star Wars" trilogy, the "Lord of the Rings" trilogy, "The Lion King" and "The Godfather" also fail the test.

Tarquini, who is also the executive director of the Bath Film Festival, launched F-Rated in 2014. Several film festivals have adopted the rating since that time, but IMDb is the most significant group to date.