OpenGL (Open Graphics Library) is a standard 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. OpenGL was developed by Silicon Graphics and is 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, flight simulation and video game development.
OpenGL 2.0 was conceived by 3Dlabs to address concerns that OpenGL was stagnating and lacked a strong direction. 3Dlabs proposed a number of major additions to the standard, the most significant of which was GLSL (the OpenGL Shading Language, also slang). This would enable the programmer to replace the OpenGL fixed-function vertex and fragment pipelines with shaders written in a C-like language, massively expanding the range of graphical effects possible. GLSL was notable for making relatively few concessions to the limitations of the hardware then available; this harkened back to the earlier tradition of OpenGL setting an ambitious, forward-looking target for 3D accelerators rather than merely tracking the state of currently available hardware. The final OpenGL 2.0 specification includes support for GLSL, but omits many of the other features originally proposed which were deferred to later versions of OpenGL (although many are now available as extensions)