Should I use www?

The short answer is, it doesn't really matter, as long as you're consistent and forward the alternative to your main domain.

If you'd like to know more about the background to this question, read on. The subdomain www is a subdomain of the highest level of your site, e.g. for the domain example.com it is the full domain www.example.com. Historically www was used for websites, and other subdomains might be used for other purposes (for example mail. for a mail server or ftp. for an ftp server), in practice nowadays most websites serve on both www and the bare domain, and www is somewhat redundant. Browsers like safari now omit the www when quoting the domain in the address bar, and many prominent sites use the bare domain (twitter.com for example), so the www seems to be slowly dropping away.

As with every question on the internet, you can find someone with an opinion on either side, in fact people have even registered domains about this - www.no-www.org and  yes-www.org in order to wage holy war about the lack or not of www.

Consistency

You should always choose one domain for your website to live on, and redirect from any other domains to that domain. This is known as the canonical url, and also applies to content on your site - you should not serve the same content on several different urls - instead choose the one you wish to be the canonical url and redirect other content to it.

So whichever version of your website you choose - www or bare domain, you should always redirect from the other to your preferred name. This lets users use either www or the bare domain when visiting your site without problems. People *will* link to the wrong version of your url, so be sure to handle it and redirect to the one you prefer.

“Canonicalization” is a big word that Google may or may not have made up to refer to “the process of picking the best URL when there are several choices.” No matter which format you decide to use, the important thing is to be consistent and help search engines determine the “canonical version” (ie. the version that best represents your entire site).

Google's opinion

The official word from Google is that it doesn't matter, as long as you're consistent and redirect from one to the other. If you redirect one will be recognised as the canonical domain and the other one ignored. You're not going to be penalised in searches as long as you forward from one domain to the other.

Our opinion

We agree that it doesn't really matter as long as you're consistent and redirect from www to the bare domain or vice versa. Many sites nowadays choose to forgo the www as it does seem rather redundant, particularly with new tlds which mean your domain can tell a story without spurious words like .com or www. So our choice would be to use the bare domain and drop the www, but make sure you forward www urls.