Positioning systems determine the location of a person or an object either relative to a known position or within a coordinate system. In the last few decades, various positioning systems have been motivated by demand and developed. This chapter provides an overview of the main positioning techniques: time of arrival (TOA), direction of arrival (DOA) and received signal strength indicator (RSSI). It then introduces positioning systems that are either in use or being developed for a variety of applications. Operations of these positioning systems are summarized using flowcharts and figures. In addition, the chapter compares positioning systems on the basis of system characteristics and performance parameters. Many of these positioning techniques and systems are introduced in greater details throughout different parts of the handbook. The chapter concludes by reviewing a number of emerging positioning systems and outlining some future applications.