The websites which have duplicate content on the web has increased tremendously. And more than you can imagine, this content does not come from other websites but happen on the same domain of the same website. This article looks at what duplicate content is all about, canonicalization and how to use free tools to deal with this issue. Whereas the intention of this post is about duplicates in general, the ones on your own website are more important than those off it, according to ranking experts.