Structural chemistry of biomolecular hydration via computer simulation: The Proximity Criterion Abstract: Use of the proximity criterion (the partitioning of the solvent space into the Voronoi polyhedra defined by the solute atoms) for the analysis of computer simulation data on solutions is demonstrated through various examples drawn from recent work. A general formulation that is based on the concept of Ben Naim's quasi-component distribution function concept and includes the definition of properly normalized radial distribution functions is also presented.