  In future cellular systems, wireless localization and sensing functions will
be built-in for specific applications, e.g., navigation, transportation, and
healthcare, and to support flexible and seamless connectivity. Driven by this
trend, the need rises for fine-resolution sensing solutions and cm-level
localization accuracy, while the accuracy of current wireless systems is
limited by the quality of the propagation environment. Recently, with the
development of new materials, reconfigurable intelligent surfaces (RISs)
provide an opportunity to reshape and control the electromagnetic
characteristics of the environment, which can be utilized to improve the
performance of wireless sensing and localization. In this tutorial, we will
first review the background and motivation to utilize wireless signals for
sensing and localization. Next, we introduce how to incorporate RIS into
applications of sensing and localization, including key challenges and enabling
techniques, and then some case studies will be presented. Finally, future
research directions will also be discussed.
