The BBFC is responsible for classifying films shown in British cinemas according to their content and suitability for different age groups. There are 7 different classifications ranging from U for universal to R18 for explicit adult content. The document discusses the criteria for each classification level, focusing on the types of content that determine if a film receives a 12, 15, or 18 rating such as violence, language, drug use, sexual content, and imitable behavior. It then analyzes a hypothetical film and determines it would receive an 18 rating due to its depictions of drugs, violence, criminal behavior, and language.