14 DAY TRIAL // Many web developers are asking themselves if their domain is more useful like http://softpedia.com than http://www.softpedia.com. You're probably already thinking that you must buy 2 domains, one with "www" tag and one without it.
As usual, Google helps you if you want to get your website indexed by their service, by allowing you to redirect the visitors from first example to the second one, or vice versa.
The feature is entitled "preferred domain" and "is the one that you would liked used to index your site's pages (sometimes this is referred to as the canonical domain). Links may point to your site using both the www and non-www versions of the URL (for instance, http://www.example.com and http://example.com). The preferred domain is the version that you want used for your site in the search results."
"If you choose don't set an association, we may treat the www and non-www versions of the domain as separate references to separate pages. If you choose a version, we use that information when crawling links to your site that use either version of the URL. We also use the information to help us determine how to display URLs for your site in the index," Google says.
Vanessa Fox, Google employee, sustained that you must "consider all links that point to the site (whether those links use the www version or the non-www version) to be pointing at the version you prefer. This helps us more accurately determine PageRank for your pages."