The BBFC rates films and videos in the UK to indicate their suitability for different age groups. They watch each film in full before assigning a rating of U, PG, 12, 12A, 15 or 18. These ratings provide guidelines for viewers and retailers on the appropriate audience for each film based on its content. The BBFC considers issues like violence, language, sex, drug use and more to determine the rating. They provide case studies examining their classification process and decisions for specific films like Frozen, Black Swan and The Exorcist.