Kathryn Page Camp
My answer? "Get it out of your head and onto paper or a computer drive." The minute you put it in tangible form, it's copyrighted.
"But don't I have to register it with the government or something?"
You can. But no, you don't have to. There are advantages to registering, but they are too complex for a blog post. The process can also be time-consuming and expensive, especially if you register multiple copyrights.
Including a copyright notice on the material is enough to keep most people from "borrowing" it. That's because the average person doesn't know the copyright law and doesn't realize that something is copyrighted unless he or she sees a notice on it.
A copyright notice consists of either the symbol © or the word "copyright," the year, and your name. For example, the notice for this post might say © 2012 by Kathryn Page Camp.
If you are worried that someone will steal your idea, registering won't help, anyway. You can't copyright ideas.
If you are worried that someone will steal the words you use to express your idea, then registering can help prove they are your words. But unless you are J.K. Rowling or J.D. Salinger, your words aren't likely to be a prime target for theft.
Still, your book could become the best seller of the century, and you should register it when it gets published. In fact, the publisher will probably do it for you.
Until then, weigh the time and money you would spend on registration against the likelihood that someone will steal your material. Only you can decide whether it's worth it.
For additional information on copyrights, go to www.copyright.gov.
My website includes a longer article on copyrights as well as other legal articles of interest to writers. You can find them under the "Legal Resources" tab at www.kathrynpagecamp.com.