The "Copyright Office"? As soon as you publish any work publicly, in any format that the public has access to, it is automatically copyrighted. No registration is required unless you want to sue someone for copyright infringement. Otherwise you don’t need to do anything.
Yup, I'm aware of that.
It's one of those pieces of advice that is legally correct but still not very smart. Put it right up there with the advisability of making a "citizen's arrest" - or walking down a city street while holding a loaded firearm in plain sight. Both acts are technically
legal in most places too.
So while it's true you don't need
to register a copyright to be technically protected by it, you do need to register in order to obtain statutory remedies. That pretty much means if you want to assert your legal rights in any meaningful way, you'll need to register. If that's not something you care about, then from my perspective, the entire issue of copyright shouldn't matter to you either.
Unfortunately, it's not just a case of whether or not you think you may ever sue somebody else. Lawsuits are double-edged swords. In this litigious world you're equally likely to be sued. So you may find yourself wishing you had registered should somebody decide to go after you claiming that your
work is infringing on their
copyright. In a showdown between two parties in an infringement case, the person who first registered is given the benefit of the doubt for having claim to the work.
Not having a registration may also create problems when you go to license or sell your work. Some clients will ask to see a copy of your registration in order to verify that what you're selling them is, in fact, yours to sell. Movie producers, national advertising campaigns, many book publishers (and anybody else who routinely gets sued) will often ask for this.
However, it isn't necessary to register each individual piece of work in most cases. You are allowed to group similar things (music, stories, art, etc.) into collections and copyright those, thereby gaining the same statutory protections you'd get by registering each individual piece.
Registering a copyright is inexpensive and very easy to do. In the USA, it can usually be done completely online.
It's a cheap form of insurance. If you think you may ever need it, don't wait until you actually do.