DirectX is a collection of APIs that provide access to the display and audio cards of a Microsoft PC.
Using DirectX, a programme can easily determine the hardware capabilities of the machine it is operating on.
These APIs provide access to the advanced features of a PC, such as 3D graphics and high-quality music and audio effects. Software is hence able to run on any Windows-based computer with DirectX compatible hardware and drivers.
The name DirextX was coined as shorthand for the multiple APIs that make up the technology.