Event driven programming mechanism.
It responds to messages by processing messages send by OS.
Events may be keystrokes, mouse click etc.
WinMain() is the entry point to windows program. It creates the window and retrieves and dispatch the messages to appropriate window procedure.

Features:
Message Processing:Every Window Prog. Must have WinMain() whose main task is to create the applications main window. MS-DOS based prog. Calls OS to get User input, but windows based prog processes user input via msg from OS. Common messages are WM_CREATE, WM_LBUTTONDOWN, WM_COMMAND(in response of user menu choice).
GDI Support:
Resource Based Programming:Resource files can include bitmaps, icons, menu definition, dialog box layouts etc. Linker combines these binary resource files with the c++ compiler’s output to generate executable prog. Resource editor & Resource compiler are used for programming.
Memory Management:
DLL Support:
Win32 API:
Plug and Play Facility:
GUI Support:
Support Distributed Processing:
Remote Access Through Multithreading