DirectX is a collection of application programming interfaces (APIs) created by Microsoft for Microsoft Windows.
Direct3D renders 3D graphics whilst prioritising performance. It is the main competitor against OpenGL.
Direct2D renders 2D graphics and vectors. It can interoperate with Direct3D.
DirectWrite renders text.
DirectCompute supports general-purpose computing on graphics processing units.
 DirectX Media
DirectX Media includes DirectAnimation, DirectShow, DirectX Transformation and Direct3D Retained Mode as-well as DirectX plugins for audio signal processing and DirectX Video Acceleration.
 DirectX Graphics Infrastructure
DirectX Graphics Infrastructure provides a mapping between graphics APIs and the graphics kernel.
 Complementing Software
Checks for the newest version of DirectX and installs the latest version.
 DirectX Diagnostics
A tool for diagnosing and generating reports on components related to DirectX.