If you have a site which generates a number of URLs for the same page, this (IMO) shows a need for a CMS which would resolve this issue, or investigation how you can resolve the issue permanently leaving just one page in the index. As you point out 301 is the best way (or if you’re building a site from scratch – don’t duplicate your URLs ).

I think that while Google haev introduced this tag to make webmaster’s lives easier, they may have shot themselves in the foot by providing a tag that it is very easy to implement incorrectly. I may be proved wrong though…

@L. Mohan Arun

“My opinion is that, the canonicalization is something that the search engine spider should be intelligent enough to sort out on its own.”

The fact that the cannot do this is the very reason this tag was created. I’d suggest reading the ‘futher reading’ links provided. It isn’t really just to do with SEO, if you have the kind of duplicate content issue Lisa describes, all those pages will simply be excluded from the search engine’s index.

If you’d actually read this post you’d know that this comment “…that require webmasters to go in and put in all the canonicalization tags in every page of the site” is somewhat off the mark.

http://www.vervesearch.com &
http://www.vervesearch.com/index.php OR http://www.vervesearch.com/index.html OR
http://www.vervesearch.com/index.asp

are all the same page.

Does anyone know why this doesn’t happen? Is it to do with the fact you can have diferent pages as your default document in a folder, so Google is never sure whether this is the case? Surely it could check?

Cheers,
Sam