Optimization is an integral part of engineering design. Traditionally, optimization tasks have been carried out mostly by trial and error, when unexpected failure of a design to meet certain criteria is identified. Often, a best design is not obtained after many design iterations. Only a feasible design meeting all the requirements is created. The conventional way of changing a design when it is found to be deficient in certain criteria can be incredibly costly and time-consuming. For today's engineers, a more productive and cost-effective practice is to use numerical optimization techniques to guide in the evaluation of design trade-offs. Often, a best design is put forward after running simulation-based optimization a few times. In this chapter, we will cover materials relating to the topics of design optimization via simulation. The concepts of topology optimization, parametric optimization, and design space exploration will be introduced, along with optimization examples using ANSYS® Workbench.