In order to use OpenGL with Win32 to render images, there are some initialization steps that must be taken. These steps are outlined below. Before creating a window, a window class must be registered. A window class is a basic template that is used to create a window in an application.
Every window is associated with a window class.
Multiple windows can be associated with a single class. When the application that registered a window class exits, the window class is destroyed. The window class contains the window procedure . A window procedure is a callback function that is used by Win32 to notify the application of messages that should be processed by the window. See the next section on messages for more information about window procedures.