Don't let some of these people ruffle your feathers.......OpenGL (Open Graphics Library) is a specification defining a cross-language cross-platform API for writing applications that produce 3D computer graphics (and 2D computer graphics as well). The interface consists of over 250 different function calls which can be used to draw complex three-dimensional scenes from simple primitives. It is very popular in the video games industry where it competes with Direct3D on Microsoft Windows platforms. OpenGL is widely used in CAD, virtual reality, scientific visualization, information visualization and video game development. Simply, it is a 3D graphics rendering protocol that is not dependent on Microsoft Windows Directx or other proprietary software. It is open source code and can be used in most operating system platforms. Good question, by the way!! Hope that helps!