What is ww2/www2 in the URLs

I have recently noticed some sites with URLs having ww2 or www2. What are they? Is there anything new that came up recently? Is there any link where I ca开发者_Go百科n get more information on that?

While www2 may just be a subdomain, it can also be a type of load balancing or mirrors:

http://en.wikipedia.org/wiki/WWW2

This url's just shows that these websites are made using free web hosting sites or its just a subdomain.

If you talk about things like www.example.com, ww2.example.com or somethingtotallydifferent.example.com. That is just a subdomain.

No one tells you how you have to name the servers in your zone, www is just a convention for a webserver.