To qualify for copyright protection the only requirements are that an item be an original work that is “fixed in any tangible medium of expression.” In short, once you’ve hit save on your file, uploaded it to a server, put a doodle down on a napkin or otherwise fixed your idea into some tangible medium, it is copyright protected.

There is no registration requirement, no need to mark it with a symbol or even to indicate that it is copyright protected at all. If you created, it simply is protected and you hold the copyright in it.