What is WINVER?

Question

I was looking at some code and they had this line: #define WINVER 0x0501 in stdafx.h file? Why do you need to define WINVER? How does

Answer 1

WINVER defines the minimum Windows system the program can run on. There's a more detailed explanation at MSDN. What #define WINVER 0x0501 means is that the program requires Windows XP or Server 2003 to run, and that it therefore can use Windows functionality up through that release.