RSSWhy should I copyright my work?
Internet Filmmakers' FAQ
Your work is copyright from the moment you create it. You cannot choose to have something copyrighted...
The issue is whether you will want to pursue a breach of that copyright. If someone copies your work... you can either ignore it or you can try to take action.
The are companies/registries in each country that will register your intellectual property, but this only serves as "evidence" incase you need to prove that you were first to create it if a dispute arises.
As to the question of why you would want to copyright your work... there are various reasons. The most important two are:
1. Financial - If the work makes money, you may be entitled some of it.
2. Creative - You will want to be properly acknowledged for your work. It could help your reputation and/or your success for future work in the industry.