Google & Bing Disagree On Rel=Canonical Implementation
Bing recently posted an article: Managing redirects – 301s, 302s and canonicals
As someone that works with Enterprise level sites on a regular basis, I deal with duplicate content & the canonical tag a lot. What really jumped out in Duanne’s article is this (emphasis added is my own):
Something else you need to keep in mind when using the rel=canonical is that it was never intended to appear across large numbers of pages. We’re already seeing a lot of implementations where the command is being used incorrectly. To be clear, using the rel=canonical doesn’t really hurt you. But, it doesn’t help us trust the signal when you use it incorrectly across thousands of pages, yet correctly across a few others on your website.
A lot of websites have rel=canonicals in place as placeholders within their page code. Its best to leave them blank rather than point them at themselves. Pointing a rel=canonical at the page it is installed in essentially tells us “this page is a copy of itself. Please pass any value from itself to itself.” No need for that.
This surprised me as it contradicts what we’ve been told by Google, and also contradicts my opinions on best practices for the canonical tag. I have a deep respect for Duanne, so I’m only raising this as an issue because the rel=canonical tag is supposed to be jointly supported by Google & Bing, yet we’re getting very different direction on how it should be used.
For instance, in this Google Webmaster Help video (H/T to James Constable for the link), Matt Cutts says “it doesn’t hurt to have this on every page of your site.”
Likewise, in the Google Blog, Maile Ohye of Google says “Yes, it’s absolutely okay to have a self-referential rel=”canonical”. It won’t harm the system and additionally, by including a self-reference you better ensure that your mirrors have a rel=”canonical” to you.”
Further evidence Google says its okay to have both a self-referential rel=canonical tag as well as to use the canonical tag site-wide can be found in this SEOmoz post, as well as another Google Webmaster Help video from Matt Cutts saying its okay.
I asked some of the top SEO minds on Twitter as to their opinion, and they all seem to support the notion that is okay to use the canonical tag site-wide and include self-referential canonical tags. Here are their responses:
@Thos003: I use rel=canonical on it’s own page to deal with URL strings. I find this article disturbing
@rbucich: of course you can! Either I don’t understand the question or the person who said no doesn’t
@ajkohn: Yes. I think rel=canonical is a safeguard for HTML barnacles that might attach themselves to the canonical URL.
@james_constable: YES it needs to for all ad tracking, parameter non sense you need to avoid dups.
@dannysullivan: i wasn’t aware this was a problem. i guess i don’t see that it is. google said it wasn’t bit.ly/pxoxwx
@halvorsen I do.
So, it seems were at an impasse – what are your thoughts – is it okay to use the rel=canonical tag sitewide? Is it okay to use the rel=canonical tag on the canonical version of the page?
Will you change your recommendations to clients (or your own sites) on how they should use the rel=canonical tag based on Bing’s latest blog post?
Your comments are appreciated.
**Update @MattCutts chimes in:
@nickroshon certainly it won’t mess things up with Google to do it on every page. Can’t speak for MSFT/Bing, of course. (link)
@nickroshon self-loops on canonical pages are fine. Otherwise you’re stuck doing per-page logic for every page; not fun. (link)
**Update 2: This post has gotten some great conversation going, and also picked up by a few other sites, so I wanted to link out to that as well. It appears the SEO community finds this to be an important issue, and it’s obvious duplicate content is the thorn in everyone’s side…thanks to all that have shared my post!
- Google & Bing See Canonical Tags Differently Barry Schwartz shares my post on Search Engine Roundtable – I’m absolutely stoked to see my post on a blog I respect so much (and read every day!)
- Do Bing & Google Treat Rel=Canonical Differently? John F Doherty adds his take, hypothesising that Bing’s algorithm is not as sophisticated as Google’s when it comes to understanding self-referential canonical tags, hence the difference in messaging from Bing versus Google.
- Canonical Tag on Every Page: A Tale of Two Engines NorthsideSEO wrote a similiar post to mine at around the same time – another well written post on the subject.
- My post on Sphinn – I’ve been Sphunn’d!
- How does Google handle the canonical tag? the iCrossing UK blog Connect shares their take on my blog post
- Recap: Really Informative Articles Tweeted This Week – thanks for including me, Search Engine Journal!