The history of OpenGL
Almost ANY 3d card as of today can handle the standard OpenGL programming language (Even my now-crappy Rendition Verite 2200 can !) so there’s no need to worry about compatibility.
Why you should need it ? Well if programmers want to make their 3d work in almost any known configuration without having to program a lot of workarounds for every hardware , they stick to a recognized standard. OpenGL is such a standard , as is DirectX for MickeySoft’s products.
OpenGL however also works on Linux/Unix , Suns , Mac’s and SGI’s graphical cards.
One of the commonly known OpenGL products is the rotating teapot.