The Brittish Board of FIlm Classificaion must give every film a certificate before it's screened in cinemas to protect the people watching.
Wiki:The British Board of Film Classification (BBFC), originally British Board of Film Censors, is a non-governmental organisation, funded by the film industry and responsible for the national classification of films within the United Kingdom. It has a statutory requirement to classify videos, DVDs and some video games under the Video Recordings Act 2010.
|Universal||All ages admitted, there is nothing unsuitable for children.|
|Parental Guidance||General viewing, but certain scenes may be unsuitable for children under 8.|
|12A||May be unsuitable for under 12s. Those aged under 12 are only admitted if accompanied by an adult at all times during the performance (cinema only).|
|12||Suitable only for those aged 12 and over.|
No-one younger than 12 can rent or buy a 12 rated VHS, DVD, Blu-ray Disc, UMD or game.
|15||Suitable only for those aged 15 and over.|
Nobody younger than 15 can see a 15 film in a cinema. No-one younger than 15 can rent or buy a 15 rated VHS, DVD, Blu-ray Disc, UMD or game.
|18||Suitable only for adults.|
Nobody younger than 18 may see an 18 film in a cinema.
No-one younger than 18 can rent or buy an 18 rated VHS, DVD, Blu-ray Disc, UMD or game.
|Restricted 18||For adults only.|
May only be shown at licensed cinemas or sold at sex shops, and only to people aged 18 or over.