It is an open-source raytracing program. According to
www.povray.org , "Ray-tracing is a rendering technique that calculates an image of a scene by simulating the way rays of light travel in the real world."
Basically you can take the pretty flat and lifeless models you create in AC3D and get something more like those at
http://www.povray.org/community/hof
HTH,
AJ