Q. If you mail yourself a copy of your manuscript and then never open the package, is that the equivalent of an official copyright?
A. No. What you’re talking about is called “poor man’s copyright.” I don’t know who first perpetuated this myth, but it is indeed a myth.
Q. Are there different kinds of copyright?
A. Two kinds, basically. To put this simply, there is the “guaranteed copyright” you get whenever you write anything down, and there is the official copyright (think of it as a “super copyright”) you get when you register with the national office in DC. The difference between the two is that having a “super copyright” (which will cost you approx. $45/work) will allow you to sue for more money and damages should you ever have to sue.
Q. Should I include the copyright symbol on my work?
A. If you’re submitting to agents and editors, no. They know that the material is owned by you, so including the mark is the sign of an amateur. However, if you are giving your work to fellow writers or putting it online, yes yes yes.
Agents and editors don’t steal work; writers steal work.
Q. In general, what can I do to protect myself?
A. Don’t put your work online unless there is a good reason to do so. If you post a short story online so people can get a taste of your skill and voice, you are letting your idea out there. People cannot cut and paste paragraphs of your work, that’s for sure, but they can take your concept or idea and give their own spin on it.