The Open Graphics Library (OpenGL) is a standard specification defining a cross-language, cross-platform Application Program(ming) Interface (API). OpenGL provides the programmer an interface to the graphics hardware. OpenGL is a powerful, low-level rendering and modelling software library.
With OpenGL it is possible to produce 2D and 3D graphics applications.
OpenGL is widely used in video games, CAD, scientific applications, etc, on many different platforms.
Many commercial games, such as the ID Software's Quake series, use OpenGL for their graphics engines.
In the 1980's developing software was a challenge. Especially when you wanted to program for a wide range of graphics hardware. (Remember, at that time there were no API's that could be used).
The software developers had to write custom drivers for each piece of hardware. They also had to deal with a lot of different interfaces, which made the task even harder. (The development cycle was slow because of it). Another problem was that each development team (from different companies) had to write drivers for the same piece of hardware. The result was that there was a lot of the same source code been written by different teams. (Waste of time and money).
In the early 90's Silicon Graphics inc. was a leader in 3D graphics for workstations. They used an API called IRIS GL for their workstations. IRIS GL was proprietary to SGI's hardware and not an "open" standard. The API was considered to easy to use and it also supported immediate mode rendering.
At that time competing vendors, including Sun Microsystems, IBM and Hewlett-Packard were also bringing 3D
hardware on the market. They used another API called PHIGS. (In funcionality and capability IRIS GL was superior to PHIGS).
Because other vendors brought new 3D hardware on the market, SGI's market share became smaller.
To turn the tide and influence the market SGI decided to turn the IRIS GL into an open standard. (They could not make IRIS GL an open standard because of licensing and patent issues). They made a new API based on IRIS GL called OpenGL.
In 1992, SGI led the creation of the OpenGL architectural review board (ARB). (The founding companies of the ARB were: SGI, Microsoft, IBM, DEC and Intel. Today nine companies have voting seats on the ARB, and several more attend the quarterly meetings to provide input to the evolution of OpenGL). The role of the OpenGL ARB is to establish and maintain the OpenGL specifications.
Not all advanced hardware-specific features can be accessed by the OpenGL versions (default Opengl).
(Remember, a new version of OpenGL is not released very often). Fortunately, the video-card manufactures can and do provide OpenGL extensions. With these extensions you are able to access advanced hardware-specific features.
If these features are used by many vendors, the extensions can become an official addition to the OpenGL standard. (In an old version (OpenGL 1.2) an advanced feature (add that time) was requested by game developers called multi-texturing).
Future releases of OpenGL will be more and more influenced by game developers and the gaming industry.