Persistence of Vision Ray tracer or POV-Ray is a rendering engine for Computer Graphics of great quality, distributed under a FREEWARE license (should be 'Open Sourced' with the 4.0 version).
This engine is based on the raytracing technic, and offers a great variety of functionalities helping to achieve realistic renderings. You can pay a look to Xavier Michelon's article on the raytracing to get more background on this technic (french version only, sorry).
Unlike 3D softs like Blender or Moonlight, POV-Ray is only a rendering engine. This means it doesn't provide any GUI to help modeling your scene. In fact, scenes are written using a native script langage. For many people, it is quite difficult to describe a 3D scene the very same way you code a piece of software, so a wide variety of graphical tools have spread (modelers for the most part) in order to create these scene for you. Unfortunately, these tools were mainly intended for the Windows O.S. For example, even the Windows version of POV-ray comes with a text editor able of highliting the text in color and a rendering GUI while the Linux version is only available in command line. Moreover, like Moray, most of the tools available are sharewares, and even the few freewares are not Open Source and not shipped with the sources.
Now, after a long wait, there are tools fully usable with a GNU/Linux system and many others are at different stages of development. The information you will find in this website is all about POV-ray and its usage on a GNU/Linux system.
The up-to-date version of POV-Ray is the 3.5.
The last beta-test version is the 3.6 Beta 2.
The topic of the POV-Ray section is based on the Biscuit.pov image created by Fabien Mosen. This image was used with the kind authorization of Fabien Mosen.
Caustic test, by André Pascual
Example rendered by Gilles Tran