It comes a time in the start of any web business to pick a domain name. This is a laborious task in itself, since pretty much all the cool domain names that resonate with your business are already taken either by the existing competition or by domain pirates.
It was the case with Teamness and after the domain was chosen and we were about to wipe the sweat off our foreheads, we ran into the unruly question of which URL should we promote: www.teamness.com or teamness.com ?
There are many pros or cons on neither of them. Some believe it's better with the www prefix, others think it's nicer without.
The most important thing is to pick one in the beginning and stick to it. We don't want the links pointing to us on the web to be either with www.teamness.com or teamness.com.
Another important thing is that no matter what the visitors are typing, www.teamness.com or teamness.com, they must reach Teamness nevertheless. We think it's incomprehensibly rude to punish someone who typed teamness.com by sending them to the error page. So a redirect from one form to the other is mandatory.
We chose www.teamness.com over teamness.com and one reason had to do with subdomains: we post ramblings to blog.teamness.com, the private stuff is located at my.teamness.com and probably we'll use more subdomains in the future, so the www form acts as a disambiguator.
There is, however, a technical issue with the www-less domain. The cookies will be set for the whole domain. Each cookie has a domain and a path and the browser sends the cookie to the domain specified in there. If the domain is www.teamness.com, the cookie will not be sent to blog.teamness.com, but if the domain is teamness.com, then the cookie will be sent to all subdomains, like blog.teamness.com, my.teamness.com and so on.
Few people use the www prefix in verbal communication as it became implied when referring to a website. Also, when you type the name in the address bar and hit Ctrl+Enter, every browser will add the www. Prefix and append .com.