Canonical Link Element

So what is a canonical link element or canonicalization?

It’s a link element, an open standard, and is supported by Microsoft, Google, Yahoo.

A canonical link element is a way to define a canonical page which is the preferred version of a set of pages with very similar or duplicate content.

It fixed all the cracks and mistakes developers make in their code.

Make all your internal links consistent. Make sure your URL’s are standardized or normalized. In other words don’t have different versions of your URL’s in your internal linking.

For example all of the URL’s below can be the same exact page but search engines will be confused and see them as different pages even if they return the same content.

Because in practice they can actually return different content depending on the content management system and the web server.

www.yourdomain.com
www.yourdomain.com/index.html
www.yourdomain.com/
www.yourdomain.com/index.html/
index.html

The best thing maybe be to always use absolute URL’s. For example always point to your home page like so…

http://www.yourdomain.com/index.html

This way you are consistent and you don’t confuse the search engines and seem like you have duplicate content.

If you do have different internal linking and or duplicate content that you can’t fix it then you use the canonical link element in your web pages.

The way to specify the canonical page is to insert the link element like this ..

<link rel=”canonical” href=”http://www.domain.com/index.html”/>

You can self-reference a page. Meaning you can insert the above link element in your index.html page and on any page that duplicates the index.html. When you insert it in index.html it’s a self reference.

One of the biggest issues I’ve seen with code and with content management systems sometimes is that the entire site points to the main page. So all pages are pointing to the index page.

This can be detrimental to a site. I’ve seen this happen and the entire site is not indexed except for the index.html. So what do you do in this case? Remove the line of code and resubmit your website to the search engines.

Here is an article on How to Remove Canonical Link Element From Multiple Files.