Simply put: For VFR traffic, if inactive, it's equal to Class G. If
active, it's equal to class E.

If you don't want to talk to the airport to which a particular air space
belongs, then assume it active, i.e. Class E. Which means that you
should expect IFR arrivals or departures and look out and behave
accordingly. No clearance required, but if you talk to the tower, they
will (or should) provide you with information about IFR traffic.

Stefan