The last several decades have seen increases in patenting activity worldwide, as well as growing issues related to patent quality. In response to these quality issues a recent patent literature has emerged, that investigates the behavior and incentives of patent examiners, applicants, and third parties. In this paper, we provide an overview of patent procedures, patent systems and a survey of the new economic literature on patent systems. Both theoretical and empirical papers are considered. Policy implications coming from this literature are presented.