Confused about rel="canonical"

[BrandonC-269887]

I'm receiving a duplicate content error in my reports for www.example.com and www.example.com/index.htm. Should I put the rel="canonical" on the index page and point it to www.example.com? And if I have other important pages where rel="canonical" is being suggested do I place the rel="canonical" on that page? For example if www.example/product is an important page would I place on that page?

[BrandonC-269887]

I haven't considered this option, thanks for the tip.

[BrandonC-269887]

I've read that a 301 redirect hurts your page rank. Is that true? Thanks for pointing me to that page. I've seen and read that page a long time ago and at the time it was like a foreign language. Now it makes more sense.

[Highland]

I dunno that Google gives you a good example of why you would use it, just where. Canonical, for all intents ard purposes, lets you pick which of your duplicates gets indexed.

Here's a real world example. Newegg.com has, literally, tens of thousands of products. Their site is in site.com/?id=STRING but they do a lot of URL based tracking. As such, you have a lot of site.com/?id=STRING&ref=1234 Now, Google will see all of those extra query string pages as unique pages with duplicate content. Newegg uses canonical to ensure that Google ignores all but the core product page.

So, why use a 301 and why use canonical? A 301 removes the page from the index. Canonical leaves the page indexed but transfers PR to the "real" page and helps avoid duplicate content.

[RyanOD]

To expand on what Petra said, have you considered using your .htaccess file to permanently redirect all version of your home page to www.example.com (and other pages as well)? This can be done in conjunction with rel="canonical".

SEOmoz offers a Redirection Best Practices doc that can help you out.

[petrakraft]

To your first question:
www.example.com/index.html --> use a 301 redirect to www.example.com

Regarding rel canonical --> there the usage is explained pretty well:
http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html

You add the tag to specify your preferred version inside the section of the duplicate content URLs.