Mm-wave and massive MIMO technologies are some of the elements that have enabled the increase of the communication capacity and reliability, and the reduction of the latency in 5G systems. These technologies have also made possible the advent of new positioning solutions characterized by very high accuracy, provision of orientation information, and inclusion of sensing capabilities, with reduced network-side infrastructure. The term “5G Localization” was coined to encompass this class of solutions, which have already impacted the standardization process. Elements considered in the ongoing research towards 6G systems, such as reconfigurable intelligent surfaces (RIS), are also showing large potential for localization, as they extend the position availability to problems that were previously unfeasible. First, this talk will briefly present the foundations of radio-based positioning and an overview of the evolution of localization in cellular standards. Second, it will dwell on some specificities of 5G localization: single base-station and carrier-phase positioning, 6D problems, and signal design. Finally, it will address how the presence of RIS in the near or far field can be exploited for localization.