The second you create an original work, you own the copyright for that work. It does not need to be registered for you to have ownership. It is your intellectual property.
But what if you want someone else to have control over the copyright? Or maybe you want to license some of the rights so someone else can use the asset? How does that work? Does the U.S. Copyright Office have some kind of special process in place or forms for you to use?
In fact, you do not even need to record your transfer with the U.S. Copyright Office to make it valid. There are many legal advantages to doing this, though, such as validating the transfer against third parties.
Moreover, the transfer of exclusive rights to another party is not valid unless you document that transfer in writing and it is signed either by the owner of the copyright or the authorized agent of that owner.
Even this comes with some leeway. For example, if you verbally agree to allow someone to use your copyrighted material and questions arise about the legality of their use of the copyright, it is sufficient to draft a written document at that point confirming that the rights were indeed transferred, assigned, or licensed.
Furthermore, if you are transferring a right on a non-exclusive basis, there does not need to be any written agreement at all, although this could lead to legal problems in the future if you have nothing in writing.
Additional methods of transferring copyright ownership include bequeathing it in your will and having it passed on as personal property to the person of your choice. A copyright may also be conveyed by the applicable laws of intestate succession in the state in which you live if you do not have a will.
Remember, copyright is a personal property right. Because of this, it is subject to the various state laws and regulations that govern the ownership, inheritance, or transfer of personal property, as well as terms of contracts or conduct of business.
Why does any of this matter? If you need to bring an infringement suit in federal court against someone who is using your copyrighted work without permission, the owner of the copyright needs to show proof of an unbroken chain of title going back to the author of the work. In other words, you will need to provide those written documents showing the transfer from each person to the next until the copyright was given to you.
As you might imagine, this is where recording transfers with the U.S. Copyright Office becomes particularly useful.