what is the use of windows.h code example

Example: windows.h

windows.h is a Windows-specific header 
file for the C and C++ programming languages 
which contains declarations for all of the functions 
in the Windows API, all the common macros used by Windows programmers,
and all the data types used by the various functions and subsystems.
It defines a very large number of Windows specific functions that
can be used in C.