This book presents conventions, mathematical concepts, definitions and applications central to the geometric modeling of solids, shells and wires (engineering jargon) embedded in 3D space. Currently, software is available for geometric modeling of technical or natural scenarios. However, the models built frequently fail in supporting the subsequent engineering computing and simulations. Only after repeated iterations and re-design, the models permit engineering / science simulations. This book endows the reader with the basic mathematical concepts needed to ensure that the geometric models indeed stand the stages of physics simulation, manufacturing, etc., and rapidly applies the concepts on engineering and science geometric models.