The British Board of Film Classification (BBFC) is a non-governmental organisation founded by the British film industry in 1912 and responsible for the national classification and censorship of films exhibited at cinemas and video works (such as television programmes, trailers, adverts, public information/campaigning films, menus, bonus content, etc.) released on physical media within the United Kingdom. It has a statutory requirement to classify all video works released on VHS, DVD, Blu-ray (including 3D and 4K UHD formats), and, to a lesser extent, some video games under the Video Recordings Act 1984. The BBFC was also the designated regulator for the UK age-verification scheme, which was abandoned before being implemented.

The BBFC was established in 1912 as the British Board of Film Censors, under the aegis of the Incorporated Association of Kinematograph Manufacturers, by film trade associations who preferred to manage their own censorship than to have national or local government do it for them. The immediate impetus for the board's formation stemmed from the furore surrounding the release in the UK in October 1912 of the film From the Manger to the Cross, about the life of Jesus. The film, shown at the Queen's Hall, London, gained considerable publicity from a great outcry in the Daily Mail, which demanded: "Is nothing sacred to the film maker?", and waxed indignant about the profits for its American film producers. Although the clergy were invited to see it and found little to be affronted by, the controversy resulted in the voluntary creation of the BBFC, which began operating on 1 January 1913.

The Cinematograph Act 1909 required cinemas to have licences from local authorities. The Act was introduced for reasons of public safety after nitrate film fires in unsuitable venues (fairgrounds and shops that had been hastily converted into cinemas) but the following year a court ruling determined that the criteria for granting or refusing a licence did not have to be restricted to issues of health and safety. Given that the law now allowed councils to grant or refuse licences to cinemas according to the content of the films they showed, the 1909 Act, therefore, enabled the introduction of censorship.

The film industry, fearing the economic consequences of a largely unregulated censorship infrastructure, therefore formed the BBFC to take the process 'in house' and establish its own system of self-regulation. By paying a fee of £2 for every reel of film viewed, and by appointing a panel of viewers under a censor, none of whom had any film trade interests, the growing cinema industry neatly created a censorship body which was both self-supporting and strictly impartial, and therefore was not swayed by any sectional interests inside the film trade or outside it. The board's offices were originally at 133–135 Oxford Street, London; the building is located at the junction of Wardour Street, a centre of the British film industry for many years.

Unlike the American Production Code Administration, which had a written list of violations in their Motion Picture Production Code, the BBFC did not have a written code and were vague in their translation to producers on what constituted a violation. However, some clarity would come in 1916 when the then president of the BBFC, T. P. O'Connor, listed forty-three infractions, from the BBFC 1913–1915 annual reports, during the National Council of Public Morals: Cinema Commission of Inquiry (1916), indicating where a cut in a film may be required. These included:

In 1926, the BBFC annual report outlined grounds on seven broad categories that justified censorship, including issues related to religious, political, military, social, questions of sex, crime and cruelty. Some decisions from the early years are now subjected to derision. In 1928, the board's examiners report famously claimed that Germaine Dulac's surrealist film The Seashell and the Clergyman was "almost meaningless", but: "If there is a meaning, it is doubtless objectionable."

Informal links, to varying degrees of closeness, have been maintained between the BBFC and the Government throughout the Board's existence. In the period before the Second World War, an extensive but unofficial system of political censorship was implemented by the BBFC for the Home Office. As the cinema became a socially powerful mass-medium, governments feared the effect of its use by others for propaganda and as happened in the Soviet Union and Nazi Germany discouraged any expression of controversial political views in British films. This trend reached its climax during the 1930s. Following protests from the German Embassy after the release of a film depicting the execution of Edith Cavell (Dawn, 1928, dir. Herbert Wilcox), intense political pressure was brought to bear on the BBFC by the Home Office. A system of script vetting was introduced, whereby British studios were invited to submit screenplays to the BBFC before shooting started. Imported Hollywood films were not treated as strictly as British films, as the BBFC believed that audiences would recognise American cinema as representing a foreign culture and therefore would not apply any political messages therein to their own lives. So while the Warners gangster films and other 1930s Hollywood films that dealt explicitly with crime and the effects of the Great Depression were released in the UK largely uncut, these subjects were strictly off-limits for British film-makers.

During the Second World War, the BBFC's political censorship function effectively passed to the Films Division of the Ministry of Information, and the BBFC never regained this to the same extent as before the war. The increasing climate of post-war liberalism ensured that from the 1950s onwards, controversies involving the BBFC centred more on depictions of sex and violence than on political expression. There were some notable exceptions: Yield to the Night (UK, 1956, dir. J. Lee Thompson), which opposed capital punishment; Room at the Top (UK, 1959, dir. Jack Clayton), which dealt with class divisions; Victim (UK, 1961, dir. Basil Dearden), which implicitly argued for the legalisation of homosexuality, all involved the BBFC in controversy.