Impact of certification of film openings

Why do we have certification?

We have certification on films to stop inappropriate content being viewed by younger and more innocent eyes. This means that each film has it's own rating, U, PG, 12, 12A, 15, 18, R18 - so that no one under the age of this ratings can view the film; it also allows a review for parents and guardians to see whether the film is suitable.

This affects the way film openings can be made as the opening has to be able to shown on daytime television for any body to watch. This means that a film has to either put parts of the film that can be shown to younger audiences, or they can put part of the film that aren't suitable for younger audiences however will have to show it after 9, which is after watershed and means that they lose a lot of audience / advertisement. Certification affects what can be shown in the film opening.
Similarly, certification can affect the type of genre that a film opening is made out to be. The film might be a horror, however will only be shown after 9 at night because of the genre that it is in. This means that certification also  affects how often a film opening can be shown during the day, depending what genre the film is.