Introducing Canonical Linking – Why it’s important for SEO

Canonical Linking : Introduction

In 2009, the key search engines announced that they will begin supporting the use of Rel=Canonical links. For web pages that have multiple URL’s for the same page or even the same content, Rel=Canonical links will specify to search engines which version of a URL should show up in the search results pages. The Rel=Canonical tag is located in the HTML header of a web page as seen below:

<link rel=”canonical” href=”http://www.ElevateSEM.com/news” />

If you were to take a look at a website not using a Rel=Canonical link for a particular page, you may notice that you can get to the same page through various different ways – type in the URL, link to it through a navigation bar, etc. In many cases, these different ways of reaching the page will lead to the same page, but that same page may have various different URLs. See below for some examples of different URL’s for the same page:

http://www.example.com/service.php?item=lawn-mowing

http://www.example.com/service.php?item=lawn-mowing&category=yard-services

http://www.example.com/service.php?item=lawn-mowing&category=yard-services&category=services

Why is the Rel=Canonical Link Important?

Although these links listed above lead to the same content, one page may be more up-to-date than the other. If links are being built to this particular page, you will want to make sure that the links are being built to the correct URL! Adding this link into the code of your webpage will help ensure that the popularity of your various links is consolidated to your preferred version of that page. In the world of SEO, there aren’t many definite answers from the various search engines of what will help rankings on the search results page, just techniques that have been theorized and proven. This is why anytime a major search engine makes a statement that something will help websites, we listen very closely! Furthermore, as posted on Google’s Webmaster Center Blog regarding the Rel=Canonical link: “It’s a hint that we honor strongly. We’ll take your preference into account, in conjunction with other signals, when calculating the most relevant page to display in search results.” (http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html)

[testimonial name="Randfish" function="SEOmoz.org"] …in my opinion, the biggest change to SEO best practices since the emergence of Sitemaps [/testimonial]

Wistia

Should You Use Rel=Canonical Links

So why would you not use these Rel=Canonical Links? This all seems like a no brainer, right? Well, what happens to all the links that you have built on other websites when they are built to one of the URL’s that you are not using a Rel=Canonical Link on? Other websites may link to your webpage using URL’s that are canonically inconsistent. Now you have to hunt down all of these sources and get them to change their link URL’s, right?  If you have an existing site with lots of external and internal links, all using different canonical URLs, then rel=canonical is easy fix that can be placed right on the target page. Now you don’t have to worry about tracking down every link source – every link is automatically redirected to the correct URL! For those of you who are familiar with a “301 redirect,” these two links may seem strikingly similar. Which one should you use? Discover the benefits and downfalls of both on another SEOmoz article “http://www.seomoz.org/blog/301-redirect-or-relcanonical-which-one-should-you-use).

How to add a Rel=Canonical Link to your Webpage

To specify a canonical link, you must determine all duplicate URL’s to the page at hand and add a tag into the HTML header of all of the duplicate pages. In the <head> section of all URL’s with duplicate content, add this link to specify your desired version of that page:

<link rel=”canonical” href=”http://www.example.com/service.php?item=lawn-mowing

This will ensure that all of these duplicate URL’s will link directly to the main URL of that page at:

http://www.example.com/service.php?item=lawn-mowing

A full guide on Google’s support page can be found here (http://support.google.com/webmasters/bin/answer.py?hl=en&answer=139394). For more questions on this visit our SEO Services Page and ask for a free consultation.

1 Comment

  1. July 28, 2012

    [...] to have dealt with Canonical Linking, check out one of the previous articles on the Elevate Blog: Introducing Canonical Linking – Why it’s Important for SEO. “Canonical Alerts have been enabled because we see a lot of misuse of the rel=canonical tags. [...]