Search engines can see variations of the same domain as different pages and this can cause confusion and possible ranking reductions. For instance, domain.com, domain.com/default.asp, www.domain.com/default.asp, and www.domain.com can all be seen as different pages, even though they are actually the same page. Typically a server-side redirect can be implemented to point all of these domain variations to one main domain. You may, do search engines care which domain variation I should use. The short answer is no. As a standard, we typically redirect all of our client’s websites to the www.domain.com.
Definition of canonicalization - The process of converting data that has more than one posiible representation into a “standard” representation
Tags: url canonicalization, seo, search engine optimization, canonicalization