Which pages should use rel="canonical" links?

[COfashionista]

I have many pages showing up as multiple content. Most of the them belong to product pages for my store, login pages that show up everywhere on the site, etc. I know that I need to use the rel=canonical link in the header but after searching the forum I'm still unsure of what pages need it. Is it the pages that I don't want searched/crawled by Google or the other way around?

Thanks!

Crystal

[Highland]

If you have duplicate content, Google only wants to keep one in their index. It used to be that Google would just pick one but, with canonical, you can pick. Pick what page you want indexed and then put a canonical with the URL of the page you want to keep on the other pages. Google will then keep the page you wanted and ignore the rest.

A visual guide here

[COfashionista]

Perfect, thank you! This will be my homework for the evening.

Crystal

[PatioLifeStyle]

Follow-up questions:

[1] My site development tool (XSP) has recently added the canonical reference as an auto-generated line of code, every page of my site now has it. Why is SEOmoz warning me that I have hundreds of pages of canonicals if it's supposed to be a GOOD thing?

[2] Google is still seeing the pages without the canonical tag because that's how they were indexed. Will they eventually get purged from their index, or should I be proactive about that, and if so, how?

Thanks for any input.

[Highland]

You shouldn't be getting warnings. They appear as notices in my campaign and they're there to let you know that the spider found them. The reason you need to know is that canonical has a downside: crawl budget.

Bots still have to crawl your canonical pages. If you add content on a frequent basis, this could impact how quickly that content gets indexed. It's always better to have fewer pages but, when you can't avoid it, there's canonical. That's why SEOMOZ tracks it for you.

[PatioLifeStyle]

Yes, you're right -- they are notices, not warnings. Thanks for the response.

Do you have an answer for my #2 question?

[Highland]

Google will still crawl canonical pages. How soon the index will reflect that will depend on how fast that crawl happens. I'm not sure there's anything you can do to speed that up.