Plagiarism has become a serious problem on the Web. If you have a successful website, it is almost guaranteed that someone will imitate it sooner or later. In many cases, your content will be copied and after making some minor changes, these websites will claim it as their own.
There are simple steps that you can take to prevent this from happening. Make sure to display a copyright notice on your website (©). If your website’s content is of value to you and you want to make sure it is legally protected, it may be a good idea to copyright it with the U.S. Copyright Office (http://www.copyright.gov/) you can do it online and the process is fairly straightforward. For more information, take a look at their Copyright Registration for Online Works manual.
It is also a good idea to actively monitor the Web for copies of your content. There is a free search engine called Copyscape (http://www.copyscape.com/) that is dedicated to search for copies of your content on the Web. Just type in your URL and it will find other websites that may have content similar to yours. They also have commercial monitoring available.