This book focuses on video-based, corneal-reflection eye trackers - the most widely available and affordable type of system, and takes a look at a number of interesting and challenging applications in human factors, collaborative systems, virtual reality, marketing and advertising. The third edition has been extensively revised and extended, and includes new chapters on calibration accuracy, precision and correction; advanced eye movement analysis; binocular eye movement analysis; practical gaze analytics; design; GIS. Opening with useful background information, including an introduction to the human visual system and key issues in visual perception and eye movement, the author then surveys eye-tracking devices and provides a detailed introduction to the technical requirements necessary for installing a system and developing an application program.