Abstract
This chapter provides the concept of modular design, which is a design technique that can be used to develop complex products using similar components. Modular design can be viewed as the process of producing units that perform discrete functions, and then connecting the units together to provide a variety of functions. Moreover, this chapter provides the concept of modular design, modularity, product modularity representation, the modular systems development process, the product development process using the design structure matrix, and finally, a complete description for DSM building.