every COM object supports atleast one interfaceie IUNKNOWN 
interface.each interface supports method acess data and 
perform operations transperantely to the programmer,example 
iunknown supports 3 methods addref(),release
(),queryinterface().if p is apointer to any iunknow.p-
>addref()increments the reference count
2)release().p->deleting the obkects when the reference 
count reaches zero.,
3)queryinterface(idesired,pdesired).p->checks to see if the 
current interface supports another interface