A reset controller is a linear controller whose output is reset to zero whenever its input and output satisfy an appropriate algebraic relationship. It has widespread industrial applications and is used in many modern day control systems. This monograph provides a comprehensive survey into three parts. Part I provides an historical literature review and presents some fundamental results. Part II deals with nonplanar reset systems and covers several reset rules that may be used to augment high-order controllers for plants of any order. It also provides several simulation studies showing that reset control strategies may allow to attain better performance with respect to the optimal ones obtained by classical continuous-time controllers. Part III focuses on planar systems and reports on a nontrivial generalization of the basic mechanisms emerging in Clegg integrators and First Order Reset Elements (FORE). Relevant case studies emerging in the automotive field are included. This monograph gives an in-depth assessment of the state-of-the-art and provides the reader with a starting point for further research into the increasingly important topic of Reset Control Systems.