void** in relation to QueryInterface??

[SimplySane]

The function prototype for QuerytInterface is this:

 STDMETHODIMP QueryInterface( REFIID riid, void** pIFace )

And calling the QueryInterface function is like this:

pICreateCar->QueryInterface( IID_IStats, reinterpret_cast<void**>( &pIStats ) );

What's confusing me is the casting of the address of pIStats to void**
reinterpret_cast<void**>( &pIStats )

What exactly is void** in this context?? Why do we cast the address of the interface ptr to void**??

Thanks!