Copyright is a convoluted topic with a complicated past. The mysteries and intricacies of copyright law are best left to a copyright attorney, not a mere mortal like me. (In other words, this post is not legal advice.)
First, some copyright basics. An author, photographer, or creator of any other work does not have to apply for copyright. It is automatically granted in the original US Constitution (Article I, Section 8). Just like you don’t have to apply for other rights granted in the Constitution, you don’t have to apply for copyright. It’s an inherent right. Nobody issues copyright; no bureaucrat in flowing robes bestows it upon you. However, you can register your copyright with the US Copyright Office, which is a department of the Library of Congress. Registration gives you more legal leverage if someone infringes on your copyright. It proves who created the work and when. (By the way, it’s a myth that you can mail yourself a copy of your work and not open the envelope as a way of securing copyright.)
The only requirement for you to have copyright protection is to record your work in a tangible form. For example, if you and I go to lunch and I scribble a drawing on a napkin, I immediately own the copyright because the napkin is tangible. I can either choose to register my copyright or not. Either way, I own the copyright. But if we are at lunch and I tell you a story that I dreamed up but I never recorded it anywhere (in writing, in a digital file of some kind, in an audio recording, etc.), I do not own the copyright because spoken words are not tangible. You are free to use my story any way you want to, including for profit, and I have no legal right to stop you.
You don’t have to publish your work to make your copyright effective. As long as it’s in a tangible form, even if you hide it under your mattress and never show it to anyone, you own the copyright. And you don’t have to write copyright or include the copyright symbol or anything else on your work. The mere fact that it’s in a tangible form is enough (although it’s a good and common practice to include a copyright notice).
If someone is commissioned to create a work, or if a person is an employee of a business, their work is generally considered work for hire, and the commissioning party or the employer owns the copyright. For example, if I hire a graphic designer to create a logo for my business, that is considered work for hire and I own the copyright (such agreements are best put in writing ahead of time because there can be exceptions, such as with photographic portraits). Or, if I am an illustrator for an advertising firm, any drawings I produce are owned by my employer. The employer owns the copyright, and I have no legal claim to my own work. That is standard practice in most employer/employee relationships and is often included in hiring contracts or employee manuals.
I could go on and on, but I’ll save topics like fair use, public domain, and permissions for another day. In the meantime, if you need more information, check out the following resources:
Friedlander, Joel. The Self-Publisher’s Quick and Easy Guide to Copyright. Marin Bookworks, 2012.
Peterson, Elsa. Copyright and Permissions: What Every Writer and Editor Should Know. New York: Editorial Freelancers Association, 2012.