The BBFC

The British Board of Film Classification (BBFC), originally British Board of Film Censors, is the organisation legally responsible for film classification within the United Kingdom.

It was believed to be responsible for video and some video games until August 2009.

The BBFC currently issues the following certificates. The category logos were introduced in December 2002, replacing the previous ones that had been in place since 1985.
Certificate
Name
Definition

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
Suitable for those aged 12 and over. 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, only to people 18 or over

http://en.wikipedia.org/wiki/British_Board_of_Film_Classification