There seems to be a lot of confusion with using WWW or not using WWW with your website URL. Does it matter one way or another? The answer is no it doesn't matter if you add the WWW before your website URL or you decide to eliminate the WWW before your website URL. Today this is a personal preference and it is up to you to choose the way you present your site's URL to search engines. However, you do this, you must stick with it and always use the same URL no matter what. If you've already submitted your site's URL to a search engine, it is necessary that you continue to use the same URL in order to benefit from the small things and not have your site banned for double content.
Changing Your URL:
If you have submitted your website to a search engine using www.site.com and now have decided that you want to just use site.com, the search engine will now consider this two different websites and will ban your site for double pages, content, and also keywords.
Long ago when the practice of link purchasing was widespread there were a lot of questions concerning adding www to the beginning of the URL address a site used. In the early days, the confusion leads to a lot of link failure and caused webmasters a lot of trouble on the sites they built. Webmasters needed to monitor the site to make sure that the two different options weren't considered the main mirror by the search engines.
What Are The Differences?
If a website uses www in their hostname it will adjust the DNS which will restrict the cookies while visiting or utilizing other domains. This is a technical privilege given to sites that add the www before their URL hostname.
If your website doesn't use www before the hostname, you are not granted the same privileges as a site that uses www before their hostname. When you choose your URL hostname it is recommended that you speak the name out loud and decide if you like www.site.com better than you like site.com. Just keep in mind that a harmonic name is easier for a person to recall and remember when they are searching for your site online.
Today it is more important for you to concentrate on the SEO of your site and not so much on having www in front of your URL hostname or not. The www doesn't have any significant benefits if it is added to your URL hostname or not. The only thing you need to worry about when setting up your URL hostname is to make sure that you clearly clarify the website URL when it is registered and you keep the same website URL when registering with the different search engines.
Does Google Care?
If you are wondering if Google cares about you adding a www before your hostname or not, the answer is no. Google doesn't care one way or another. All Google cares about is that you continue to use the same hostname all the time and not change it. If you've registered your website using www before your hostname, this is what Google wants to see when you register your site. They don't want you to register your site without the www in front of your hostname.
So now you see there is no benefit in adding the www before your URL hostname. This is your personal choice one way or another and it doesn't matter how you decide. The only thing that matter is that whatever you decide, you stick with your decision for the life of your site.
What do you prefer a www before your hostname or just your hostname without a www?