When setting up your domain name, it doesn’t matter if you use the www or not. What does matter is that you pick one and commit; On all of your online and off line material.
The reason you should stick with one has to do with SEO (Search Engine Optimization). It doesn’t matter which one you pick, however, in the eyes of Google, www.mysite.com is not the same as mysite.com, even though both will take you to your site. By using both, some search engines might “think” that you have duplicate content and will penalize your site for this.
Picking the best URL — when possible — is called canonicalization. Canonicalizing not only helps to let Google know that you do not have duplicate content but also helps with your PageRank, and PageRank is all about inbound links (including links from within the site). PageRank is Google’s way of deciding a page’s importance. Liken the number of inbound links to a site to the number of “votes” that site is receiving. The more votes a site gets the more Google thinks it must be an important site. Note, however, that PageRank is only ONE of the many factors that determine your site’s ranking in the search results. It isn’t the only factor that Google uses to rank pages; Quality, and relevant content, in many ways is the most important factor.
As an example of what happens to your PageRank if you use both the www and non-www: If you have 100 inbound links to www.mysite.com and 300 inbound links to mysite.com then you will have a different PageRank for BOTH URLs causing you to lose valuable inbound links since they will be split between the www and the non-www.
Some considerations when choosing:
Backlinks: First things first. Unless your site is brand new and has not yet been indexed by the search engines, it may not be possible for you to select between the www and non-www. Do a Google search for your site and take a look at your inbound links. If the bulk of your high quality “backlinks” are to “www” then that will be the URL you will want to use.
Print collateral: If all of your print material and advertising contains one version of your domain name over the other you may want to change that as well. You can do that on a moving forward basis since you should also be doing what is known as a “301 Redirect” from one to the other.
After you’ve decided, the next step is:
Do a 301 Redirect. A “redirect” is when someone types in the URL that you did NOT choose, or clicks on an old link to a page they found while doing an internet search, and are automatically redirected to your preferred domain name. This is also done when you have registered several different domain names and have all of them point to (redirected) your chosen URL. (Sidebar: DO register variations of your domain name to prevent anyone else from setting up a domain name that is very close to yours.) Google has information, and a video, with instructions on how to do a 301 Redirect if you would like to do this yourself. The best method is to use “301 Moved Permanently” with the .htaccess text as this will make sure that search engines will combine the value of your inbound links.
Google Webmaster Tools: If you use Google Webmaster Tools, remember to revise your account configuration to match your choice of URL. Go to “Tools” select “Set Preferred Domain” and choose the www or non-www domain.
