Well here’s the question whether to use WWW or non WWW url with your domain? Which is better? What’s the impact on SEO? I think it doesn’t matter. But what ever you choose stay with one. Either redirect your www domain to non www or non www to www domain.
From the perspective of SEO it doesn’t matter which on you choose. Both http://www.yourdomain.com and http://yourdomain.com are treated equally. If you want a more detail read here . If you use both and don’t redirect to any one then google consider both http://www.yourdomain.com and http://yourdomain.com as different site and may penalize your site for duplicate content. So from the start of your site stay with one. You can inform google which one to index via Google Web master tool. Since I am using WordPress SEO by Yoast it will automatically handle this for my WordPress site. It’s a very handy SEO plugin that I recommend for your WordPress sites. Also make sure you have your preferred url in your WordPress dashboard settings in Settings->General->WordPress Address (URL) and Site Address (URL).
When to use WWW in your domain?
I personally prefer non www version. Because it makes my url shorter and we don’t always have to tell that there is www ahead of my domain. But if you website is too large i.e millions of visitors, it is recommended to stay with www version. It has particular advantage over non www which is also called as naked url. For more detail read this http://www.yes-www.org/why-use-www/ But I tend to stay with naked url as my blog will never reach that large audience 🙂