Scope of sessionStorage and localStorage

I read some documentation on sessionStorage and localStorage, but I don't understand what the scope is: the domain, a specific page?

For example, if I have the following pages:

http://example.com/products.aspx?productID=1

http://example.com/products.aspx?productID=2

http://example.com/services.aspx?serviceID=3

And if on each of the above pages I run (with idvalue being the value in the querystring):

localStorage.setItem('ID',idvalue);

Am I going to end up with 3 different values stored, or are the values going to overwrite each other?