DirectX

Microsoft DirectX is a collection of APIs for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms.

Originally all API names started with "Direct" in their names (Direct3D, DirectDraw, etc.), thus the name DirectX was coined as a shorthand term for all of these APIs (the X standing in for the particular API names) and soon became the official name of the collection.

WinG
WinG can be more or less seen as a predecessor of DirectX. It was also intended to provide faster graphics performance, but for Windows 3.1x. It was soon discontinued in DirectX's favor.

One well-known application using WinG acceleration is Microsoft Bob.

Components
DirectX is composed of multiple APIs, the most commonly known ones as follows:
 * Direct3D (D3D): Real-time 3D rendering API.
 * Direct2D: Current 2D graphics API.
 * DirectDraw: Deprecated 2D graphics API.
 * DirectSound: Deprecated Audio API (replaced by XAudio2 and XACT3).
 * DirectX Diagnostics (DxDiag): A tool for diagnosing and generating reports on components related to DirectX, such as audio, video, and input drivers.
 * DirectX Media for Audio/Video acceleration (deprecated).
 * DirectWrite, a Text rendering API.
 * DirectInput, an input API for interfacing with keyboards, mice, joysticks, and game controllers (deprecated).
 * DirectPlay, a network API for communication over a local-area or wide-area network (deprecated).
 * DirectX Ray Tracing (DXR): Light ray-tracing API.

Versions
DirectX 4 was never released. Raymond Chen of Microsoft explained that after DirectX 3 was released, Microsoft began developing versions 4 and 5 in parallel. Version 4 was planned as a short-termed release with minor changes, whereas version 5 would've been a bigger release. Due to the lack of interest from game developers in the DirectX 4 features it was soon canceled, and the large amount of documents that already distinguished the two new versions resulted in Microsoft choosing to not re-use version 4 to describe features intended for version 5.
 * DirectX 1 (1995; 1.0 shipped with Windows 95 RTM)
 * DirectX 2 (1996; 2.0a shipped with Windows 95 OSR2 and Windows NT 4.0)
 * DirectX 3 (1996; 3.0a shipped with Windows 95 OSR2.5 and Windows NT 4.0 SP3; last release for Windows NT 4.0)
 * DirectX 5 (1998; 5.2 shipped with Windows 98)
 * DirectX 6 (1999; 6.1a shipped with Windows 98 SE)
 * DirectX 7 (2000; 7.0 shipped with Windows 2000; 7.1 shipped with Windows Me; last release for PCs with 486 processors and last version to have built-in RGB software rendering support)
 * DirectX 8 (2001; 8.1 shipped with Windows XP and Windows Server 2003; last release for Windows 95 and last version to have software rendering support in DxDiag)
 * DirectX 9 (2004; 9.0c shipped with Windows XP SP2, Windows Server 2003 SP1 and R2; last version for all Windows versions below Vista and Server 2008; Windows 98 and Windows Me support already removed after the December 2006 revision)
 * DirectX 10 (2006; 10.0 shipped with Windows Vista and Windows Server 2008)
 * DirectX 11 (2009; 11.0 shipped with Windows 7 and Windows Server 2008 R2; last version for Windows Vista and Windows Server 2008; 11.1 shipped with Windows 8 and Windows Server 2012 and partially backported to Windows 7 and Windows Server 2008 R2 with the Platform Update)
 * DirectX 12 (2015; 12.0 shipped with Windows 10 and Windows Server 2016, followed by DX12 Ultimate in 2020, which shipped with Windows 11)