In this chapter, we consider the design of localization algorithms for reconfigurable intelligent surface (RIS)-aided models under different practical channel model settings. More specifically, we utilize the compressed sensing (CS) to localize user equipment (UE) direction and position in both far-field and near-field multipath environments respectively; we extend our work by performing a super-resolution localization using the atomic norm minimization for a user located in a single and path near-field channel. On the other hand, we propose RIS phase design that aims to minimize the localization error by maximizing the signal-to-noise ratio (SNR).