International copyright law is a bit different than U.S. copyright law. In the U.S., you can register your copyright with the U.S. Copyright Office. However, in most other countries, you do not have to register your copyright. Your work is automatically copyrighted as soon as it is created. Some countries have treaties with the U.S. that recognize U.S. copyrights. This means you can enforce your copyright in those countries even if you don't have a registered copyright. Other countries do not have treaties with the U.S. and do not recognize U.S. copyrights. This means you cannot enforce your copyright in those countries. If you want to register your copyright in a country that does not have a treaty with the U.S., you will need to do so through that country's copyright office.