This document discusses adaptive cruise control (ACC) systems for vehicles. It begins by defining ACC as a system that helps vehicles maintain a safe following distance and speed automatically without the driver having to adjust. It then discusses the different sensor technologies used in ACC systems, including radar, laser, and multi-sensor systems. The document also covers types of ACC like predictive systems and the advantages of ACC in increasing safety and traffic flow. It concludes by noting some limitations of ACC systems in adverse weather or environmental conditions.