Why use $ (dollar sign) in the name of javascript variables?

Possible Duplicates:
Why would a javascript variable start with a dollar sign?
JQuery : What is the difference between “var test” and “var $test”

What is the difference between this two ways of initializing variables?

var $val = 'something'

     OR

var val = 'something'

as I see they are the same thing.

Maybe in this case $ is only the part of name in variable? (it will become a meaningless question in that case:/)

Thanks