In product design and manufacturing process planning, we prefer the “best” product design out of all feasible designs, which is called the optimal design. Optimization techniques have become the major quantitative tools in engineering design and decision-making process. Process optimization is a process that adjusts a current process to optimize some specified sets of parameters without violating constraints. The most common goals are minimizing cost while maximizing profit and efficiency. This chapter introduces the formulation of a design problem as an optimization statement incorporated with the design constraints. Essential computational methods for solving the optimization statements with demonstrated examples are also discussed.