This chapter introduces the different ways of conducting usability evaluation, which is categorized under four methods: model or metrics based, inquiry, inspection, and testing. Under each method, a list of techniques is described, focusing on when and how each technique should be applied. The chapter also summarizes various studies that compared the effectiveness of different usability evaluation techniques. At the end, guidelines for practitioners and an agenda for researchers are offered. After reading this chapter, the audience should gain an overview of the research and practice of usability evaluation and understand the different criteria for selecting the appropriate technique for a particular project.