__declspec( ) and _imp__

if you are writing a DLL and you want to make the
symbol available in the export table WITHOUT using the DEF file:

__declspec(dllexport) int FooBar();

if you are writing a component and you want to use a function that is
implemented a DLL:

__declspec(dllimport) int FooBar();

if you want to use a function that is implemented in a library (a real
library, not a stub library)

int FooBar();