The official government body that maintains records of copyright registration in the United States. Your work is technically copyrighted once it's in tangible form but registering it with the U.S. copyright office is an additional way to protect your copyright. In order to file an infringement action (to recover damages or stop someone from using your copyright without your permission), your work needs to be registered with the U.S. Copyright Office. Visit the USCO's official website for more information.