This book illustrates object detection and tracking technology. It encompasses a variety of problems such as noise in images, cluttered-background, complex object motion, partial or full occlusions, illumination changes as well as real-time processing requirements. These problems are studied by several tracking algorithms, which tackle them using diverse algorithms. Object tracking deals with the state estimation of one or more objects. Object tracking is required by many vision applications such as people tracking, vehicle tracking, animal tracking etc. People tracking are also done for surveillance at locations such as airports, rail terminals, landmarks, buildings, homes etc. Vehicle tracking is used in traffic monitoring, delay estimation, reroute planning etc. Tracking vehicles is one of the major importance when designing autonomous vehicles.