Direct3D is an application program interface (API) developed by Microsoft that provides a set of commands and functions for manipulating 3D objects. By using Direct3D commands, software developers can take advantage of many prewritten functions. This allows programmers to write significantly less code than if they had to write all the functions from scratch. Direct3D makes it relatively easy to manage three-dimensional objects, including lighting and shadows as well.
In order for a software program to use Direct3D commands, the computer's video card or graphics accelerator device must support Direct3D. Fortunately, just about all video cards made for PCs offer Direct3D support. While many video games and other programs use Direct3D, OpenGL is a more widely used standard.