At the heart of visualization is the representation of numeric data in pictorial form. In molecular science, data may come from acquisition, as in the case of X-ray crystallography and NMR, or from simulation, as in computing the folding structure of a new molecule. The resulting pages and pages of numbers are transformed, through the use of graphics and imaging techniques, into pictures that can better represent the underlying phenomena: catalysts represented in three dimensions, molecular interactions directly visualized, biological 'docking' of molecules interactively modeled, and new molecules designed to have maximal therapeutic effect. (3)