Link:
http://www.ddj.com/hpc-high-performance-computing/218500694Dr. Dobb's: James, what is ray tracing and why is it important?
JM: Ray tracing is a method of using "virtual light rays" to determine visibility between two points in a geometric scene. This allows for the modeling of physically accurate lighting phenomena such as reflection, refraction, soft shadowing, and global illumination, just to name a few.
Dr. Dobb's: How does ray tracing differ from rasterization?
JM: As I mentioned earlier, ray tracing can allow all of the objects in the scene to interact with each other by casting light rays between them. These complex interactions create the difference between visually pleasing images and images that are obviously "computer generated". For example, light that bounces off of a red book on a shelf can produce a reddish tint on a white wall behind it.
Rasterization, by contrast, streams all of the geometry through the pipeline one object at a time. This means that the red book has no way to know that it should tint the white wall, and the white wall has no way to know about the red book.
