Joost de Valk wrote a great WordPress plugin that I'm about to install. From Joost de Valk:
has a bunch of tracking parameters on it, and therefore is duplicate … so we may cite a canonical URL in <head> to fix this —
In this case it is the only option to do so because Google Analytics requires the page be sent, so it is not an option to simply 301 to the canonical URL afterwards. Originally I had said it was; thanks to mark @ useyourweb for pointing this embarrassing lapse in reason to me. However, with regard to server-side campaign tracking (as would be the case in non-hosted Google Analytics as well), I still maintain that it is not ideal.
The real usefulness of rel=canonical is to deal with a different (and until now unsolvable problem). When I used to work for Barry Schwartz over at RustyBrick, I discussed with him at length how to deal with 1 product in 2 categories, while maintaining state (for breadcrumbs). So if we had 1 product in N categories, we end up with N URLs —
http://www.example.com/Bar/My-Product.html
http://www.example.com/Baz/My-Product.html
Barry and I never really came up with a solution we both liked 100%. Barry?
In my book, Search Engine Optimization with PHP, I recommend setting 1 category as primary, and then excluding the non-primary URLs with a SQL query. That was the best solution I'd mustered over the years.
So let's make http://www.example.com/Foo/My-Product.html Primary, and exlude the rest in robots.txt —
Disallow: /Bar/My-Product.html
Disallow: /Baz/My-Product.html
But the problem is that it basically throws some link-equity out the window. You can't stop people from linking to the non-canonical URLs … nor can you redirect because you need the state!
But now it would seem that we can use rel=canonical to resolve that problem. So we may simply place this in the head of the document —
But it's still better to use the good ol' 301 when possible. It's computationally cheaper for search engines, so I'd expect it to work better. And it's more proven. Certain redirects in Yahoo! have been screwy for years at a time. Why chance it?
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I totally agree with this. Search engines are certainly more understood when it comes to 301s. This is a new feature. It won't have any advantages where a 301 would also be suitable, so why use it?
Jaimie, thanks for the mention. We try to not put the cat parameter in the product URL anymore. In fact, most of our newish sites should have solo product URLs, independent of the category data. But I was thinking the same thing when I heard the news of this new tag.
Maybe a stupid question but wouldn't it be possible to put noidex;follow in the meta robot tag? Instead of using a 301 redirect. Or am I way off now?
No. That wouldn't be the same thing, as excluding it wouldn't capture the link equity or inform the search engine that the pages are for all intents and purposes identical. Once you tell it that, it will probably use that as a cue to verify that you're telling the truth, and then actually calculate it that way. J.
I'm not sure how this might solve the problem. indeed a 301 would be computationally cheaper, but from the retailer perspective using a 301 probably means that the breadcrumb state wouldn't be maintained…
You give the example of Better being done with 301s than rel=canonical. Correct me if I'm wrong, but that won't work. That tracking code looks like Google Analytics. GA uses JavaScript based tracking. By 301ing that page, the client side javascript code never gets to execute, and thus never sees the tracking URL, and therefore it is not tracked. This is actually a great example of where rel=canonical would be a great solution. Or am I missing something here?
Hi, it's not related to this post but I wanted to let you know that your seo pager plugin has some serious problems - it won't validate as xhtml due to the simple reason that you forgot to put space before the href, so it actually looks like this: you should fix this.
I agree. I'm going to implement canonical links in my site right now. I just want to make sure there aren't any duplicates out there.
another thing about canonical URLs is when you use the Global Translation Plugin by nothing2hide dot net. I doesn't index translated URLs anymore. The translated pages of your site will not be included in the SERPs.
Jaimie, Great article, Have some questions and comments. I have done a fair amount of research on this issue and found that many e-comm sites are using one standard URL now for their products instead of the format you specified above. I am currently generating URLS for site in a format similar to your example but I am considering using the canonical tag and regenerating the URLS with the same path. If you have an existing site that has multiple URls for the same product you are going to have duplicate content flags set off. I can see this in google's webmaster tools. Will the canonical tag solve this? I hope so, but is there any evidence that it will at this point? My existing urls will still function but having a product with multiple urls may spread your PR juice thinly over these urls.
OK. All of this just makes my head hurt — and makes me feel lucky that our clients are mostly industrial equipment manufacturers who can't really sell their products online. But … I *am* bookmarking this page for whenever this issue comes up with one client or another, as it eventually will.
@Mark: I think you've hit the nail on the head here. Yes, it's better to use 301 redirects when you can (and it's often a big "if" depending on your technical environment), but as often as not it's not possible to readily rid yourself of parameterized URLs. And, in fact, most sites leave themselves open to possible duplicate content inflation by allowing the propagation of fallacious URL parameters (by the way kudos to seoegghead here - compare results of http://www.amazon.com/?somepareter=abcd and http://www.seoegghead.com/?somepareter=abcd). The other point worth making, I think, is that search engines don't come together to support a technology unless it helps them, so regardless of how well your 301s work (i.e. Google, which "gets" them) or don't (Live Search, which claims to "get" them but doesn't), providing the bots with clues regarding canonicalization is probably a good idea (multi-categories not withstanding).
Aren't Google now unilaterally about to reconsider the whole canonical issue, and move the goalposts again?
We're still not 100% sure search engines follow the canonical directive successfully. There's even issues with 301 redirects, let alone this new tag. Hopefully we will have some proven results soon. seomasterlist (seomasterlist)When NOT To Use Canonical URL Links: Joost de Valk wrote a great WordPress plugin that I'm about to install. Fro.. http://tinyurl.com/dbcs39 orenoque (Louis Durocher)When NOT To Use Canonical URL Links http://tinyurl.com/dbcs39 orenoque (Louis Durocher)When NOT To Use Canonical URL Links http://tinyurl.com/dbcs39 IrishWonder’s SEO Consulting Blog » Blog Archive » Ask Adds Canonical Meta Tag Support[...] sure whether to use it or not? Jaimie Sirovich provides some tips on when NOT to use the canonical URL meta tag. I would only add to his tips that I'd wait before fully relying on it as nobody can [...]
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