Here are some things you should know about copyright:
- Copyright registration is not required. It's very useful if you ever expect to go to court, but as a friend pointed out, just e-mailing the source to yourself at some public e-mail service, such as Gmail, would probably establish that you did it earlier. And you can keep your work secret too.
- Copyright is assigned automatically to you. There is absolutely no need to even say "Copyright (c) Year, Author". At least after 198x, I think.
- Copyright is available for all works, regardless of quality. It protects both your kindergarten drawings and Escher's complicated and beautiful works equally.
- Copyright covers only distribution. That should be evident from the name, but a lot of people put restrictions on use and ascribe them to "copyright". If you intend to distribute the work, for profit or otherwise, you need permission from the author. Note that if your use of the material falls under "fair-use", permission might not be required. However, fair-use is never defined explicitly, it's upto the courts to decide what exactly is fair-use.
- Copyright is limited. It expires. However, current copyright time limits are so generous that you may have to wait for a very long time for any part of current culture to fall into the public domain.
- The public domain, as a legal expression, means that there is no copyright asserted. A public domain work belongs to all, and everybody is free to do whatsoever he/she desires with it. Copyright and public-domain are mutually exclusive. You can put your works in the public domain by stating so, without having to wait for the expiry of your copyright.
