What is the API?

The API, quite simply, is the programming interface for Windows. Applications written for Windows call API functions to perform common windows tasks, such as creating and destroying windows, controls, and menus; accessing system services such as the display, keyboard and mouse input, and printing; and many other functions. Functions in the API are provided in several files known as Dynamic Link Libraries (DLLs). The DLLs in the Win32 API export, or make public, many of their functions which can then be called by any Windows application.