A target audience is the specific group of people within a target market that a product is aimed at. They can be formed using age and gender e.g. teen horrors are aimed at teenagers and certain toys like Barbie dolls will be aimed at young girls.
Audiences for horror films vary due to what type of horror it is, modern horror films have started to veer towards the teen horror category in which a group of teens are subject to a serial killer or they do something to the wrong person and they come and get revenge. The young cast means that the target audience (teenagers) can relate to them and therefore they are more intrigued to watch it. Previous horror films have generally been aimed at adults, they were certified 18 so teenagers couldn't watch them, these are films like Saw, Wolf Creek. Halloween's audience had most viewers from the age group of 18 and under (46,493) so this is the main audience for the film, it was one of the first slasher horrors and was just aimed at horror film fans.