Modern, solids-based computer-aided design/computer-aided manufacturing (CAD/CAM) systems provide a good share of what is needed for companies to develop products using modern methods. This article provides a brief history and an overview of CAD technology. Form features combined with constraint parameters have greatly simplified how designers work with solid modelers to design parts and assemblies. The article describes the four types of constraints, namely, numeric, geometric, algebraic, and attributes. It provides a discussion on data associativity and assembly design used in CAD system. CAD/CAM systems provide much more than the definition of the solid model as a design. The article provides information on the applications of CAD systems, including integrated product development, drafting and product documentation, product visualization, mechanical analysis, and numerical control programming.