Simple URL Question. Please Look!

I have seen in some sites that when you type in an address it wont go to
website unless you type in the www first. For example if I type mysite.com it
takes me nowhere, if I retype it with www.mysite.com it comes up. Why is that?

takes me nowhere, if I retype it with www.mysite.com it comes up. Why is
that?

mysite.com is the domain

www is a subdomain, and can point somewhere else.

Incompetant web site admins forget to point mysite.com at something.

-Darrel

Thanks for your reply Darrel. When you say point it at something how do you do that? Where do I go?