[codeddesign]

Technically I guess you could make it a subdomain but no one would actually do that in a production site and in my 14 years have never seen it used, not to mention that major search engine bots will lookup both. The general user will simply type in the domain name more times than not without the www

[jonhohle]

`www` used to literally be a different host in a network (and in some cases, I'm sure still is) specifically designated for WWW traffic. Think of universities in the 90s which had their existing infrastructure and an Internet facing host on their primary domain and they want to add a web server. They may have had a firewall, probably no load balances, so routing port 80 around their primary host was much more complicated than just throwing up a new host and DNS entry.

[detaro]

I regularly come across sites that only work with "www.". Common with university sites that use the subdomain hierarchy a lot. For extra fun, make the behavior reversed depending on if you are inside or outside their network.

[kuschku]

Same with my uni. And then you have sites that only work with, and others that only work without the www.

But it makes sense. the first subdomain before the uni domain specifies the faculty, many of which have their own datacenters. Then many of those have yet their own servers in their network, and often www. is one added later on.

[thesimon]

My uni makes this extra fun with different sites on http and https.

[detaro]

Oh yeah. And then someone enables HSTS and a subdomain doesn't support HTTPS, so now you have to keep a browser around that never ever is allowed to contact the parent site...