Evolution of the Windows API

The Windows API exposes the core set of functionality provided by the Windows operating system for use in applications. Primarily designed for C/C++ development, the Windows API has been the most direct mechanism with which an application can interact with Windows.

The Windows API comprises the following functional groups:

. Base Services—Provides access to the core resources of the computer, such as memory, filesystems, devices, processes, and threads

. Common Control Library—A collection of common control windows used throughout the Windows operating system, providing the distinctive Windows look and feel

. Common Dialog Box Library—A collection of dialog boxes used to execute common tasks,
including file opening, saving, and printing

. Graphics Device Interface (GDI)—Provides the facilities for an application to generate graphical output to displays, printers, and other devices

. Network Services—Provides access to various networking capabilities of the Windows operating system, including RPC and NetBIOS

. User Interface (UI)—Provides the mechanism for managing windows and controls in an application and input from devices such as the mouse and keyboard

. Windows Shell—The container that organizes and presents the entire Windows UI, including the desktop, taskbar, and Windows Explorer

Through these services, developers have had significant flexibility in creating powerful applications for the Windows operating system. However, this flexibility also bore the responsibility of handling lowlevel and often tedious operations.

With each new release of the Windows operating system, additions and updates to the Windows API were almost always included. Yet with each release, Microsoft strived to support backwards compatibility. Thus, many functions included in the original Windows API still exist today in Windows XP and Windows Server 2003.