Ian Lurie // Feb 12 2009
The major search engines just announced that they’re going to start supporting a new link attribute: ‘rel=”canonical”‘.
The Google Webmaster Central blog has a fair amount of detail, so I won’t explain it all here.
Marcelo rightly pointed out a quick refresher might be in order. Here’s what a canonicalization problem is:
Say you have a big web site with lots of pages. On most pages, you link to one critical article at:
But, on a few pages, you linked to the same page using a slightly different URL:
That difference is a canonical difference between the URLs.
You and I know perfectly well they’re the same page. But a search engine does not. So they cheerfully crawl your site, splitting link authority and relevance between the two URLs and Ralph Naderizing (or Ross Peroing) your link building efforts.
Mixing home page links between www.mysite.com, mysite.com and www.mysite.com/index.cfm can have the same effect.
It’s a major SEO bugaboo – my company has invested a lot of time and money in building a toolset just to sniff out these problems. So finding the problems aren’t that hard. Fixing them is another matter entirely, because:
So, the new rel=canonical tag could save us a lot of pain.
Or not. Read on to get my two sides of the argument: To use, or not to use.
But, ever the skeptic, I have a few things I think you should consider before diving into rel=canonical:
That said, I’m pretty damned happy about rel=canonical. It gives me an option on sites where their canonicalization looks like a bowl of dried spaghetti.
So, use rel=canonical if:
I’ll be testing out the new canonicalization tag in the coming weeks, and will let you know how it goes.
PS: I just posted a list of questions about rel=canonicalization. Go add to the list, please.
Ian Lurie is founder and CEO of Portent Inc., an internet marketing agency that has provided internet marketing, including PPC, SEO, social and analytics services, since 1995. Read More