Open Graphics Library (OpenGL) is a rendering engine for vector graphics (2D and 3D). It's a cross-language, cross-platform application programming interface (API).
The OpenGL specification describes an abstract API for drawing 2D and 3D graphics.
Although it is possible for the API to be implemented entirely in software, it is designed to be implemented mostly or entirely in hardware. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardware-accelerated rendering.
OpenGL has many language bindings: