Age certificates

The UK's film ratings are decided by the British Board of Film Classification and have been since 1912. Previously, there were no agreed rating standards, and local councils imposed their own - often differing - conditions or restrictions. For cinema releases, the BBFC has no legal power (technically, films do not even have to be submitted for classification), as it falls to councils to decide who should be admitted to a certain film, but they generally apply the BBFC's certificates, effectively making them legally-binding. In exceptional cases, councils may impose their own conditions, either raising or lowering the minimum entry age from the certificate, banning a certified film outright, or setting their own minimum entry age for films that have never been submitted for BBFC certification, or which have been refused a certificate by the Board.

U (Universal films)
The U symbol stands for Universal. A U film should be suitable for audiences aged four years and over. However, it is impossible to predict what might upset a particular child, especially at this lower end of the category range.
Films/programmes like such as Chuggington, Teletubbies or In The Night Garden are rated as U films, as they particularly targeted at pre school children.
A U film may include brief fight scenes or moments where characters are placed in danger. However, moments of emotional stress or threat will be quickly resolved and the outcome will be reassuring.
At all categories heterosexual and homosexual sexual behaviour and activities are treated the same – so there could be occasional very mild references to gay or straight sex at U.

There may be brief scary scenes and moments where the characters are placed in danger. As with violence, however, these scenes will be balanced by reassuring elements, such as comic interludes or music. Characters may be seen kissing or cuddling and there may be references to sexual behaviour (ie to ‘making love’). However, there will be no overt focus on sexual behaviour, language or innuendo. At U there will not normally be references to illegal drugs or drugs misuse unless there is a very clear anti-drugs or educational message which will be understood by a younger audience. Drugs references which are unlikely to register with young children and are brief or passing may occasionally be passed at U – for example a verbal reference to ‘the Opium wars’ in an historical documentary.

PG films
PG stands for Parental Guidance. This means a film is suitable for general viewing, but some scenes may be unsuitable for younger children. A PG film should not disturb a child aged around eight or older. Parents should consider whether the content might upset younger or more sensitive children.
There may be mild bad language (such as ‘shit’ or ‘son of a bitch’) in a PG film, but the context and delivery are always important. For example, if the language is used aggressively or if there is too much bad language, a work may be passed at the next category.
Heterosexual and homosexual sex and sex references are treated the same – so there could be mild or undetailed references to gay or straight sex at PG. References to sex are acceptable if the activity talked about or shown is implied and lacking in detail. In addition, if a child is unlikely to understand a reference, we may allow it at PG. Comedy can also often lessen the impact of sex references and innuendo.
There should be no detail of violence in a PG work, so while there might be some blood, we would not see how the injury was inflicted in strong detail. Violence is generally more acceptable in a historical or fantasy setting, because of the distancing that this provides. It isn’t uncommon for PG films to feature ‘roller-coaster’ action or set pieces, where the emphasis is clearly on the adventure or journey of the main characters rather than the detail of violence or fighting.
There might be innocuous or passing references to illegal drugs or drugs misuse in a PG work, although there should be no strong focus on this. PG films could potentially cause a child to act in a way or a behaviour in which they have seen in the film.

12A films
12A means that anyone aged 12 or over can go and see the film unaccompanied. The A stands for 'accompanied' and 'advisory'. Children younger than 12 may see the film if they are accompanied by an adult (eg someone over the age of 18), who must watch the film with them. 
The BBFC's Guidelines state that there may be strong language (eg 'f***') at 12 or 12A, but it must be infrequent. The context of the strong language is important. Aggressive uses of strong language may result in a film or DVD being placed at the 15 category. There is some allowance for puns on strong language at this category.
Sex may be briefly and discreetly portrayed at 12 or 12A. Verbal sex references should not go beyond what is suitable for young teenagers. Comedy may lessen the impact of some moderate sex references or innuendo but frequent crude sex references are unlikely to be accepted at this category. There may be nudity in 12A films but sexual nudity should only be brief and discreet.
At 12A, moderate violence is allowed but it should not dwell on detail. There should be no emphasis on injuries or blood, but occasional gory moments may be permitted if they can be justified by their context (for example brief sight of bloody injury in a medical drama).

15 films
No-one under 15 is allowed to see a 15 film at the cinema or buy/rent a ‘15’ rated DVD.  15 rated works are not suitable for children under 15 years of age. 
15 films could include any of the following:

• strong violence
• frequent strong language (eg 'f***').
• portrayals of sexual activity
• strong verbal references to sex
• sexual nudity
• brief scenes of sexual violence or verbal references to sexual violence
• discriminatory language or behaviour
• drug taking

18 films
Films rated 18 are for adults. No-one under 18 is allowed to see an 18 film at the cinema or buy/rent an 18 rated DVD. No 18 rated works are suitable for children.
18 works are for adults and can contain strong issues such as:

• very strong violence
• frequent strong language (eg 'f***') and/or very strong language (eg ‘c***’)
• strong portrayals of sexual activity
• scenes of sexual violence
• strong horror
• strong blood and gore
• real sex (in some circumstances)
• discriminatory language and behaviour

R18 films

The ‘R18’ category is a special and legally restricted classification primarily for explicit works of consenting sex or strong fetish material involving adults. Films may only be shown to adults in specially licensed cinemas, and video works may be supplied to adults only in licensed sex shops. ‘R18’ videos may not be supplied by mail order.