Censorship involves the suppression or prohibition of media content that is considered obscene, politically unacceptable, or a threat to security. In the UK, the BBFC rates films to restrict certain content to certain age groups, while the ASA regulates advertising content. There are arguments on both sides of censorship - it can protect privacy but also limits media and restricts what audiences can access. One example of a positive use of censorship is protecting the identities and privacy of criminals, like the murderers Jon Venables and Robert Thompson, after they served their sentences.