Age.

When deciding on the age restrictions for our film, we had to consider what content it would contain and what audience it would be appropriate for.18 Suitable only for adults. Nobody younger than 18 may see an '18' film in a cinema. No one younger than 18 may rent or buy an '18' rated video.
We found that our film fitted into the over 18 age boundary, this is because our film involves swearing, violence and death.

This was our first stage of working out our target audience.