Film trailers are distributed in a variety of different ways:
Television: Film trailers are regularly shown on television, they will be shown at times when their target audience is most likely to be watching television or during a break in a programme that their target audience will be watching, for example if a horror film is being advertised then it will be shown late at night during a break in a horror themed programme. A problem with showing trailers on the television is that if it is over a certain age rating then the trailer must be shown after the watershed which could reduce the amount of people that see the trailer. Showing film trailers on television seems to be becoming less popular as you cant guarantee that your target audience will see it and also the limitations in place make it harder to advertise certain films.
Cinema: Film trailers are shown alot in cinemas before films start, this is a very good way to distribute film trailers as you can guarantee that your target audince will see the trailer because film trailers are shown before films that they are similar to, for example if you are advertising a film aimed at children, such as finding nemo you will show the trailer before another kids film because you know that your audience will see the trailer. This type of distribution is regulated so that trailers with a certain age rating can only be shown before a film of the same age rating or higher. The problem with this type of distribution is the way that it is regulated may limit how many people actually see the trailer. However this is still a very popular and successfull way of distributing trailers as you can guarantee that people who enjoy watching films will view your trailer and will probably be more willing to go the cinema to watch a film.
Internet: The internet is the most popular way to advertise and vast amounts of film trailers are being shown on the internet, on websites such as youtube there are thousands of film trailers that people regularly view, even if people are not purposely looking to view the trailers there will be often advertisements on websites showing the film trailer, or at least small sections of it which may encourage someone to go on a site such as youtube and view the full trailer. Unfortunately you cannot guarantee that your target audience will view the trailer because the makers cannot control what their target audience will view on the internet, however due to large numbers of people that are viewing film trailers on the internet there is a high chance that some of their intended audience will see the trailer. One way they can make sure that some of their target audience will see the trailer is by placing it in advertising space on websites that their target audience are likely to visit, for example if it is a film aimed at younger people they will place the trailer on websites that young people are more likely to visit. Another reason that the internet is a very popular way of distributing film trailers is because there are know regulations on the internet meaning that a larger amount of people will view the film trailer, this will be especially helpful to trailers with a higher age rating.
