I'm relatively new to DirectX programming, and this is one of the more confusing issues I've encountered to date. According to the MSDN Documentation for DirectX 11:
"A device is used to create resources and to enumerate the capabilities of a display adapter."
and from the MSDN Documentation for DirectX 9:
"An adapter is a physical piece of hardware. Note that the graphics card might contain more than a single adapter, as is the case with a dual-headed display. "
From my neophyte perspective, these two concepts seem to overlap a fair amount. Am I correct in understanding that a device is an abstraction/encapsulation of a single adapter, which in turn is a software abstraction of a particular graphics card in the system?