Submitting the same content to numerous websites in order that you can get more traffic to your site is one of the main causes. When you are submitting details of your site to numerous directories then ensure that the details you submit are different for each one. The best thing that you can do when you are registering your website with any directory is to first produce 10 to 20 different detailed descriptions of it. Then as you register with each directory randomly select a description to use when submitting the sites details. Another way of avoiding this problem within a site is with the use of a duplicate content checker. There are plenty of these available online and all it requires is you to enter the URL of the site that you wish to be analyzed. Within a matter of minutes, you can see if there are any problems and if so, make the necessary changes.