I know that Blender Internal is a [scanline renderer](http://en.wikipedia.org/wiki/Rendering_%28computer_graphics%29#Scanline_rendering_and_rasterisation), but how exactly does it work? When compared to Cycles, it's much less accurate, but much faster; Also, it doesn't have the concept of sampling, so, it finishes, as opposed to Cycles, which could theoretically keep going for ever.

How does Blinder Internal work?