In the United States, like many other countries, you automatically have a copyright in a work (to the extent that it is copyrightable) as soon as you have created it. Registration of your copyright with the U.S. Copyright Office is not mandatory, but it is highly advisable to register your copyright as soon as possible after the work has been published. Without registration you can only get your actual damages, which you must prove, in a lawsuit for infringement of your copyright. Recognizing the extreme difficulty of proving or even quantifying your actual damages in a case of copyright infringement, the federal legislature created the copyright registration system to allow an alternative measure of damages in lawsuits for infringement.
Registration of copyrights in the United States
Registering your copyright with the U.S. Copyright Office grants you the right to statutory damages and attorney fees in a claim for infringement, if the registration is made within three months of publication or prior to an infringement. The availability of statutory damages means that you can get damages determined by the court, if your lawsuit is successful, starting at a minimum of $750 USD, up to $30,000, per infringement. In addition, if the infringement is found to be willful, up to $150,000 per infringement is available as statutory damages. Since the statutory damages are awarded per infringement, the amount can quickly add up in a case with a series of many infringements (making multiple copies of a work, distributing those multiple copies, etc.).
Registration of your copyright is also a prerequisite to filing a lawsuit for infringement in the United States; you must register your work before filing a lawsuit for infringement. Without registering your copyright in a timely manner after publication, a lawsuit for infringement that you may need to bring is not as strong as it could be if your copyright was registered as soon as possible. If the registration is not made within the specific time frames, you are limited only to your actual damages in a claim for infringement and you must prove these damages. While copyright registration is not required to maintain your common law copyright, there are distinct advantages in doing so, to protect your valuable copyrights.
Also, the registration of a copyright within five years of publication of the work serves as prima facie evidence of the validity of the copyright before a court.
Pre-registration of copyrights in the United States
Pre-registration is only available for certain types of works, such as computer software and video games, where there is a chance that the work could be infringed upon before it is published or released. Pre-registration was designed to provide the advantages of registration to a work before it is published, since a work can only be registered once it is published. Pre-registration allows for statutory damages and attorney fees if a work is infringed before it is published. Note that a work which is pre-registered must still be registered separately after it has been published.