Restrictions on the public showing of films may be on the grounds of obscenity, nudity, violence, or general moral undesirability, including political undesirability. Video censorship may be employed in order to prevent children from watching programmes of questionable merit at home those with excessive violence or sex, for example. However, the notion of merit is subjective, thus video censorship may be seen as a significant threat to the principle of free speech in the arts and media.
Censorship may involve cutting out certain scenes or dialogue, or may mean that the whole film is banned. The most frequent method is classifying films in various levels of acceptability: universal acceptable, adults only, teenage children, children with an adult etc. It may either be refused a licence or classification, or be confiscated. Newsreels may be censored, as may also publicity photographs for films. The banning of films may lead to the growth of private film clubs and underground cinemas. If a banned film is shown publicly contrary to the law, the exhibitor may be imprisoned.