what header files to include?

Hello …
I’m still a CUDA beginner and I want to know the header files to include in any C++ project in the .cu file (such as stdio.h in any c file)
and the importance of each file or when to include it or not to include …

knowing that I have run some programs without those include and run correctly
knowing also that the SDK projects themselves some of them include some files and the other do not

SDK 4, VS2010, toolkit 4