Many people don't seem to understand the differences between trademarks, copyrights and patents.
It's an interesting world out there, full of signs, slogans, logos, books, artistic work, and too many other things to mention in a short article. But the main thing to know is that there is a distinct difference in what a trademark is, what copyright means, and what one does with a patent.
Trademark rights act to protect a word or logo as being "the" source for goods/services. E.g. Nike. The instant anyone says that word, we all think of running shoes and well, Michael Jordan. This is the true definition of a trademark. Now here is the interesting thing. You don't need to file for trademark registration to have common law trademark rights, but let's put it this way - if you don't file and someone infringes on those rights, you'd have a tough time enforcing them. So, it's best to be safe and not sorry, and file with the US Patent and Trademark Office.
Other things that registering will do for you is provide the "presumption" you're the trademark's rightful owner and gives you statutory damages against someone using your mark in bad faith. Once your "mark" is registered, you need to remember to always keep protecting it to keep your trademark rights.
The Copyright Conundrum
The easiest way to explain copyright is to say that if you create something and it falls under the definition of being a creative work, it's up to you who makes copies and how many copies. Of course, there are exceptions, and knowing what those exceptions are happens to be important.
At this point, it's usually smart to contact a lawyer well versed in this area, as this type of law has the potential to be extremely complex. By the way, you may sell or even license this copyright, or if you have done work for someone else, then they buy this right in advance.
The major difficulty is defining what constitutes a creative work. Legally, it has to exist in some tangible form - on paper, a disk or even written in stone. However, what it's written on isn't what makes it creative. To be creative, it can't be just straight factual data; that is where an easily understandable explanation usually ends, as there honestly is even an element of creativity to coding in computer language.
Anything you do that is classified as creative writing, creative editing, etc., is copyrighted. So the distinction is this: the facts can't be copyrighted, but a very clever and creative organization of those facts may be. This is referred to as compilation copyright. In short, this area may make your head spin, so speak to a copyright lawyer who has their head on straight and can outline what you need to know.