What is DirectX 9

Microsoft DirectX (all versions) is a set of application program interfaces that allows programmers to code for hardware devices without previously knowing which hardware will actually reside on any given machine. The DirectX program does this by using a middle-man interpreter that interprets generalized commands into commands tailored for the hardware that is installed on the machine that the application is running on. Each new version of DirectX adds to the library of interfaces that the translator can translate to.