Canonical Links are the URLs in a website referring to a single webpage. To make it more clear see the below examples:
As you see, all those above URLs referring to a main page of a website examplesite.com. Search engine robots notice a smallest difference between them and treat them as a separate URL, even though all of them goes to single page.
Here is the catch, if your website’s links referring to a page which has different from other in various pages, Google will see them as a duplicate content. So to avoid duplicate content penalty, you must use one consistent and standardized URL all over your website.
Canonical URLs mostly used to avoid duplicate content penalty by Google. Because, if you strictly follow the one consistent and standardized URL pattern all over your website and how about others?. You cannot always control a guy linking to your webpage in a different way.
To make this easy and show the search engine robots that, this is a standard URL of this particular page, the element “rel= canonical” used by webmaster side a < head >tag.
See what Matt of Google explains the “rel= canonical” in-depth.
How To Setup Canonical URLs In WordPress Blogs?
Since Canonical URLs been considered as an important element to avoid duplicate contents, you must implement this in your blog. If you havent yet, start now because Google’s taking duplicate content seriously.