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Learn How to Use the New Canonical Tag and Other META Tags to Control Your SEO Search Results

February 20th, 2009 | | Crawlability, Nuts & Bolts of Optimization

With this month’s mega announcement of the new “Canonical Tag”, I thought it was high time to talk about how you can quickly and simply add tags to your website for great SEO results. Obviously, the big news is that Google, Yahoo! and Microsoft have unanimously agreed to follow the new Canonical Tag. This news effectively ends the years-long struggle to train the search engines to recognize which version of your content is the canonical one. However, there are several other helpful tags that you can apply to your websites to improve your SEO campaign – the two most popular being NOODP and NOYDIR. No, I haven’t learned a new nonsense language, these stand for “No Open Directory Project” and “No Yahoo Directory.” I’ll get to the explanations below…

The Canonical Tag

First off, what does canonical mean anyways? I like the Wikipedia definition:

Basic, canonic, canonical: reduced to the simplest and most significant form possible without loss of generality, e.g., “a basic story line”; “a canonical syllable pattern.”

As it relates to SEO, this means the “simplest and most significant form” of your website’s content. In the not-so-distant past, if you had a homepage that was located at domain.com, www.domain.com, www.domain.com/index.html, etc. – you had to not only pick the canonical form, but also implement complex 301 redirects to train the search engines on which version they should index and rank. Now you can bypass the confusion and implement the Canonical Tag – which essentially acts as a 301 redirect without the extra coding. As the always-hilarious Googlebot artwork at SEOmoz states, “It’s similar to a 301, but I don’t have to bug my dev staff as much!”

So, what exactly do you need to do? On all of the non-canonical versions of your content, insert the new tag within the <head> section of your code:

SEO Canonical Tag

This will tell Google, Yahoo! and Microsoft that they should consider the page they’re crawling as a duplicate, and move on to the canonical version for indexation and appropriation of link equity (this one’s a biggy!), etc. Note, it isn’t necessary to place this tag on the actual canonical version of your content – the tag is designed to point all the other versions back to it. For an incredibly in-depth assessment of this new tag, excellent (and hilarious) illustrations, Q&A from the search engines themselves and more on this subject, I HIGHLY recommend you read this post on the Canonical Tag at SEOmoz.


Roughly three years ago, Google announced that they would begin supporting the META NOODP tag. Three years!?! Yes, that’s an eternity in SEO years, but I thought it was a relevant time to remind readers of this tactic. When and/or if you are able to get a directory listing at the dmoz Open Directory Project, due to the strength of that inbound link – all of the search engines sometimes use that listing’s title and description as your SERP snippet. Assuming you took care when writing the title and description at dmoz, this isn’t necessarily a bad thing. However, as most of you would agree, you spend more time optimizing and carefully crafting the titles and descriptions directly on your website. Not to mention, you can change it at will to account for realignments in optimization strategy. This tag ensures that your hard work and well optimized page titles and META descriptions are used to their full potential!

By placing NOODP in the <head> section of your website’s pages, you ensure that all of the search engines will ignore the dmoz listing and instead use your well written titles and descriptions! The same principals for other META robots tags apply here – i.e. it is possible to direct these instructions to the crawlers on an individual basis (Googlebot, Slurp, etc.). The code to notify all search engines at once looks like this:




Not to be outdone by Google (well, yes they were outdone, but you get my point), Yahoo! introduced the NOYDIR tag a few months later in early 2007. For all of us who have listings in the ever popular Yahoo! Directory, the default for Yahoo! is to use that directory listing as the snippet in the SERPs. This is very frustrating, but there is light at the end of the tunnel. Like with dmoz, hopefully you carefully wrote that title and description for the Yahoo! Directory, but the one on your actual site is really the best choice!

In my experience, the Yahoo! Directory information has only been used for generating my search results in Yahoo! search. But this is reason enough to take action. To successfully block the search engines (and especially Yahoo!) from using your Directory info in the SERPs, implement the following code in the <head> section of your website’s pages:



All three of these tags are extremely helpful tools for helping you craft and control what is displayed in the search results. What does that mean for you as an SEO? When you have control over your organic listings in the SERPs, you have control to test and tweak to improve not only your ranking, but also click-through rates and overall engagement.

Does anybody have any other useful tags that you use to improve your search results? (Other than nofollow… I already know that one!)

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  • Katie

    “It’s similar to a 301, but I don’t have to bug my dev staff as much!””

    If we use this canonical tag instead of using 301 redirection would it solve this canonicalization problem??? How do search engines index our website if v can access our website using both non www or with www using this canonical tag???

    Have anyone tried using this canonical tag and seen any results.

  • http://www.seoboy.com John

    @ Katie,

    The short answer is, Yes. The big 3 search engines (Google, Yahoo! and MSN) came together and agreed to recognize and follow this new initiative. That being said, by placing the canonical tag on your homepage to state “recognize www. mysite .com as the canonical version” ***should*** be sufficient.

    Personally, I’m still stuck in 301 redirect land and have actually doubled up my efforts by both redirecting the other versions as well as placing the new tag.

    My instinct is that a 301 redirect will be the quickest way to resolve canonical issues, while the new canonical tag may take some time as a form of training for the robots.

  • http://www.pondicherrytimes.com pondicherry times

    im new to canonical tag, can you tell me , can i use in my site , what actully it use for and please clear my doubt

  • http://www.pondicherrytimes.cin pondicherry

    thank you so much, 4 month before i was searching about new cananical tag, now my fate i m getting whats in this post, thanks again :)

  • http://www.pondicherrytimes.con pondicherry

    thanks again

  • http://gogoandco.com wizzard

    I have tracking code from elements within my site on anchor text etc how do I stop that being recognized as a separate url / page.

    For example I want to measure where the clicks are coming from a landing page

    ie. /utm_source=button-bottom or /utm_source=text-body-product


  • http://www.spiffypress.com Cara

    Hi. I’m new to SEO and want to be sure I understand the use of these tags. A a huge thank you, by the way, this is the simplest most direct explanation I’ve found!

    So if I have multiple versions of my home page (w/ and w/o http://www…index.html, etc) then I’d use these tags on the versions of all of those pages, right?

    I don’t need t put these tags on all pages, right?

    Sorry if this is a really dumb question, but this newbie appreciates your help.

  • http://www.tavant.com Aby

    John – I’m new to this field, if you’d help me understand a li’ll more in detail on the Canonical tag, its purpose and applicability?

    Many thanks,

  • http://www.xportsoft.com/Services.aspx Nisha Shah

    Thanks for this post, i was little bit confused to use it. But now it’s clear.

  • http://www.devoteddomains.com Peter Bisset

    This post is really helpful, thanks!

  • http://www.faisal5i.com Faisal Iqbal

    Very useful SEO stuff, and very well cover the Canonical tag concepts.
    Definitely it prevent Search Engines to index your canonical pages.

    • Abby

      Glad you found it useful! Thanks for reading!!

  • http://www.jackwdavis.com Jack Davis

    Very useful, thanks!

  • http://www.maybray.com Maybray Digital

    I wonder what happens if you have 301 setup for certain pages + Canonical tag setup at the same time!