www or no www ?

[xene]

Why do some sites use "www" and some don't? Is it something that can be changed? How?

[TeeJa]

If it is setup in the dns zone properly, and should be by default when creating a new account, you can access a website with or without using the www.....

As an added comment, some web host don't do this, but HG does have where they will propagate to either www.yourdoamin.com or yourdomain.com. If it does not.
At one time many moons ago they where all with www.