Ref:API
From Dark Omen Wiki
An API ("Application Programming Interface") is one or more libraries with a uniform interface for an intended field of usages rather than a particular usage (compare with engine). APIs are generally an intermediate layer between lower-level (OS or hardware) operations and application code that abstracts, simplifies or organises these into higher-level calls. For instance, OpenGL and DirectX (Direct3D) are APIs for 3D graphics written on top of graphics hardware (which is usually idiosyncratic) that provides an abstracted and hardware-independent interface to using there.
