It’s amazing how one small bit of code can create such debate.

Major Search Engines Agree On New Canonical Tag discusses first the news about this new tag and then rolls right into a rollicking debate about whether or not anyone should waste their time with it.

Here are some comments:

What I think is interesting is that all the SE’s came together on this. I’m hope to migrate 80% of my traffic away from Search engines by the end of the year, and I hope others follow suit. — Glyn

This “tag” (link element) is not really meant for cross-domain usage. It’s not a way to claim ownership of content. It’s just meant for all those situations where you run into duplicate URLs within your own site and it’s hard to get them sorted with redirects.

Here are some examples where this could be used:
- Web-shops (mutliple URLs depending on how you got to a page)
- Sites that work with Session-IDs within the URL
- Ad-tracking URLs (eg using AdWords + Analytics)
- Affiliate tracking URLs
- News sites with multiple URLs per article
- Forums with multiple URLs per thread/page (eg “&highlight=”, etc) — John Mu, who works for Google

What I find most interesting – and quite amusing – is that once again the search engines are admitting failure to properly value links. — iamlost

There are many cases where the use of the Canonical Link tag would be slapping a band-aid on a broken leg, but there are also cases where using a 301 would be like applying a splint and plaster-cast to a graze. — Ammon Johns

I wonder if they’ll come out with a http Headers version to allow you to canonicalize PDFs, XML / RSS / mRSS feeds as well. — phaithful

Whether you are confused, frustrated or thrilled with this fix, the discussion is educational. Enjoy!