什么是DirectX？

　　DirectX（简称：DX）是微软推出的一套基于Windows系统的多媒体应用程式接口APIs函式。
　　在开发中，DX分为两个部分，一个是运行库，通过DX编译出来的程式必须要有运行库的支持，另外一个是开发库，也就是常说的SDK，这部分是在编译DX程序中是必需的。

详细原文介绍：

Microsoft DirectX Technology Overview
Published: March 18th, 2002

Microsoft DirectX is an advanced suite of multimedia application programming interfaces (APIs) built into Microsoft Windows; operating systems. DirectX provides a standard development platform for Windows-based PCs by enabling software developers to access specialized hardware features without having to write hardware-specific code. This technology was first introduced in 1995 and is a recognized standard for multimedia application development on the Windows platform.

What DirectX Does and How
Simply put, DirectX is a Windows technology that enables higher performance in graphics and sound when you’re playing games or watching video on your PC.

At the core of DirectX are its application programming interfaces, or APIs. The APIs act as a kind of bridge for the hardware and the software to "talk" to each other. The DirectX APIs give multimedia applications access to the advanced features of high-performance hardware such as three-dimensional (3-D) graphics acceleration chips and sound cards. They control low-level functions, including two-dimensional (2-D) graphics acceleration; support for input devices such as joysticks, keyboards, and mice; and control of sound mixing and sound output. Because of DirectX, what you experience with your computer is better 3-D graphics and immersive music and audio effects.

Windows 98, Windows 98 SE, Windows Millennium Edition (Windows Me), Windows 2000, Windows Server 2003, and Windows XP support DirectX 9.0b; the latest version that Windows 95 can support is DirectX 8.0a. For more information, please refer to the Frequently Asked Questions.