Solid modeling is the act of creating the three-dimensional models of various components and system using a computer-aided design (CAD) tool. This article describes the fundamental approaches of solid modeling, such as manufacturing operation simulation, parametric approach, and reference entities. It discusses the application of solid modeling systems to create expressions or variables and various surfaces for components. The use of high-end CAD systems to afford a number of sheet metal functions is reviewed. The article explains the explicit-parametric modeling and model verification for the solid modeling. It provides information on the application of solid modeling in associativity and concurrent engineering, product lifecycle management, and collaborative engineering.