Canonicalization - Understanding URL standardization To a spider, www.domain.com/, domain.com/, www.domain.com/index.html and domain.com/index.html are seen as different URLs, so is it better to standardise the URL you use for the website’s home page and other pages to maximise page rank? Today, Google manages this for you because it wants to minimise duplicate content, so it selects the best representative URL from the set from the one that is used most often. A recent Google blog post announced that Google crawlers identify one trillion URLs, but they don’t store them all in the index. You should use a consistent URL, typically www.domain.com, and I believe that a page with a trailing slash (and an absolute URL) is resolved and served more quickly by the server so should be used for all navigation links to pages. It also helps to standardise your web analytics reports. You can use Google Webmaster Tools to assess and manage URL canonicalization (for example, setting the ‘www' version of the site to be standard) or use the 301 redirects on Apache.
"Canonicalization - Understanding URL standardization"