some CG terms that you might get confused

1. Algorithm
ach algorithm is a list of well-defined instructions for completing a task.
http://en.wikipedia.org/wiki/Algorithm

2. Ray Casting (not to get confused with Ray Tracing)
Ray casting can refer to:

* the general problem of determining the first object intersected by a ray,[2]
* a technique for hidden surface removal based on finding the first intersection of a ray cast from the eye through each pixel of an image,
* a non-recursive variant of ray tracing that only casts primary rays, or
* a direct volume rendering method, also called volume ray casting.
http://en.wikipedia.org/wiki/Ray_casting

3. Ray Tracing
is a technique for generating an image by tracing the path of light through pixels in an image plane and simulating the effects of its encounters with virtual objects. The technique is capable of producing a very high degree of visual realism, usually higher than that of typical scanline rendering methods,
http://en.wikipedia.org/wiki/Ray_tracing_%28graphics%29

4. Scanline Rendering
in 3D computer graphics, that works on a row-by-row basis rather than a polygon-by-polygon or pixel-by-pixel basis.
http://en.wikipedia.org/wiki/Scanline_rendering