IIRC, the “www” means (or at one time used to mean) your website had been registered with IANA, where as domain.com depended on local DNS cache information. Possibly why some browsers prepend www to your domains in the title bar, also why they probably add .com, .org, .net, TLD’s to the end of a domain if you dont. Example, type in wikipedia in the address bar and some browsers will try that name under several TLD’s.

—————————-

Meh, anyway I could be wrong so here is what wikipedia says:

WWW prefix in Web addresses

“www” is commonly found at the beginning of Web addresses because of the long-standing practice of naming Internet hosts (servers) according to the services they provide. So for example, the host name for a Web server is often “www”; for an FTP server, “ftp”; and for a USENET news server, “news” or “nntp” (after the news protocol NNTP). These host names appear as DNS subdomain names, as in “www.example.com”.

This use of such prefixes is not required by any technical standard; indeed, the first Web server was at “nxoc01.cern.ch”[14] and even today many Web sites exist without a “www” prefix. The “www” prefix has no meaning in the way the main website is shown. The “www” prefix is simply one choice for a Web site’s subdomain name.

Some Web browsers will automatically try adding “www.” to the beginning, and possibly “.com” to the end, of typed URLs if no host is found without them. Internet Explorer, Mozilla Firefox, Safari and Opera will also prefix “http://www.” and append “.com” to the address bar contents if the Control and Enter keys are pressed simultaneously. For example, entering “example” in the address bar and then pressing either just Enter or Control+Enter will usually resolve to “http://www.example.com”, depending on the exact browser version and its settings.

I too hate when people are telling you their website address, and go www, it’s like omg, you don’t need to do that, or maybe they do? lol. Sad though.

Finally, must agree when people ask what site is that, and they sit down and I am telling them websiteaddress.com and they’re going okay so it’s www dot….urgh madness!