[alexshye]

Empirically, www seems to have won -- a large fraction of the top consumer sites online have picked it. One could make UI/UX-type arguments for no-www, but I sites like Facebook and Pinterest have some of the best UI/UX people in the world, and have still picked www.

What is this the case? What is the top reasons for www? Is it the cookie thing? I've heard that www lets you play DNS trics also, but haven't seen more details on this.

I'd love to hear more about this choice from people who understand the decisions at top Internet companies.

[darylteo]

I'm a convert from non-www to www. Just avoids security implications re: cookies and no need to buy secondary domain for static assets. A simple redirect mitigates the "ux" argument that the domain looks less nice to type or read. Simple implementation with more pros than cons.

Should add it's not a hard and fast rule, and depends on the use case. But the default question for me nowadays is "why no-www" and not "why www".

[the_mitsuhiko]

A www. prefix just makes life easier for everybody from just running it so there is really not much reason for not having it. Supporting the redirect is easy and people generally don't seem to care.