How Canonical Tags Are Being Abused
Written by: Nick LeRoy
A part of what makes an SEO good at what they do is their knowledge of what makes certain ranking techniques good or bad. Many of you are familiar with the rel="canonical" meta tag. Incase you are not familiar; it's a meta tag that helps consolidate duplicate versions of a page to one URL. Many of the times you will see the canonical tag implemented on E-commerce SEO projects. E-commerce sites are notorious for having huge duplicate content issues which can have a direct correlation with indexation and search engine rankings.
Canonical Tag Abuse
Looking at several sites for some inspiration for a project im working on I came across a site that offered a 'link partners' directory. Naturally I had to investigate a little more into this. This directory isn't anything out of the ordinary. The theory being that you link to the sites homepage using pre-determined html code that's provided to you. In return you get a link from their directory pointing to your site. This technique isn't new, and is very well known as a reciprocal linking. It's been said that reciprocal links offer less value then 'one way' links so many website owners have done their best to trick others into giving them a one way link. Most of the time the webmaster simply places the "no-follow" attribute to the link, uses a meta-robots file to stop the page from getting indexed or simply doesn't link the page/directory from anywhere on the site making it invisible to the search engines. This sites directory didn't use any of the above mentioned techniques, however their still guilty of manipulation. They placed a canonical tag from the directory to the homepage.
Looking at the source code for all the interior directory pages (where your link would be) you see the rel="canonical" meta tag being used and it's pointing to the homepage! This is blatant misuse of the canonical tag. Further more it is deceiving to the webmasters that link to the site with the directory in hopes of receiving a link back. This tag is ultimately preventing the linking page from getting indexed and stops them from receiving a link back.
How Is This Technique Abusive?
When you go to this sites link partners directory you see that it has an arbitrary PageRank score of 6. Sounds like an excellent directory to swap links with if its niche related huh? Now when you look at the pages Google cached version you get a copy of the homepage! The site owner is telling the search engines that this page is a duplicate copy of the homepage which is utterly false. By using the canonical tag they are allowing the page to exist to visitors but tell the search engines to consolidate its link value to the homepage. Because the page is not recognized by any of the search engines the links found within these directory pages are never indexed which doesn’t pass any value over to your site. Essentially the abusive use of the canonical tag allows this site to receive one way links through deception.
Make Sure You Don't Fall For This Trick
Some SEO’s will tell you to avoid reciprocal links altogether. In reality there are situations where you can still benefit from these links. Below are just a few tips and suggestions for seeing if a specific page is worth the effort to get a link from. This doesn’t pertain to just reciprocal links; it can be used for all link building opportunities.
Don’t trust a pages authority strictly by its toolbar PageRank. As shown above it can be gamed and is no longer the best way to measure a pages authority.
Check to see if the page your link will be listed on is indexed. If the page that will be linking to your site isn’t indexed in the search engines then no value will be passed on to your site.
How many outbound links are already listed on this page? If it’s over 50 you may want to consider avoiding this opportunity all together.
What type of sites is this page linking out to? Are they all topic related? More importantly are there sites listed that you don’t want associated with your site?