This chapter focuses on indoor localization implemented by traditional and advanced enabling technologies , measurement strategies and applications. In particular, the discussion is oriented to perform a benchmark between different solutions with a specific focus in the framework of Active and Assisted Living . A case of study of an Assistive Systems supporting blind people during the exploitation of indoor environments is also presented. The system uses ultrasound technology, an advanced trilateration paradigm to perform a real time and continuous indoor localization and tools dedicated to gain the awareness of user/environment interaction and contextualization . Such features allow to provide the user with an efficient assistance for a safe exploitation of indoor environments