Why do some urls have "www" in the address bar and others not?

[tintin99]

What's the difference between a url that has the 'www' in it and one that doesn't?

I've just created some php pages and sometimes when I browse to a url which has the 'www' in it, the browser address bar then takes it out. It's got me mystified but I'm sure there's a simple answer.

For example I go to 'http://www.mysite.com/photography' (the 'photography' folder has index.php in it) and the right page comes up but the address bar says 'http://mysite.com/photography/'

If I go to 'http://www.mysite.com/photography/' (with a / after 'photography') the browser leaves the 'www' in.

[tintin99]

Apologies! I've just realised I've posted this to the wrong forum...it's not really a javascript question is it?! Sorry!

[dcrombie]

Not really, no ;)

When you leave off the '/' the server will redirect to the "ServerName" defined for that vhost. It sounds like you have ServerName without the 'www' and a ServerAlias with.