LIDAR, otherwise known as Light Detection and Ranging, is an optical active remote sensing technique that has vast applications in numerous fields. Most impressively, LIDAR has been established as a capable tool for atmospheric studies due to its ability to probe atmospheric aerosols that are invisible to the naked eye. Although air quality monitoring stations perform admirably as atmospheric aerosol monitoring systems, the potential of LIDAR to surpass these conventional approaches in measuring air pollutant levels is evident due to its superior detection range and rapid range-resolved measurements. This monograph aims to provide an introduction to elastic backscatter LIDAR theory, design and signal processing, as well as present the reader with a review of the latest developments and applications of LIDAR in atmospheric aerosol detection. With this monograph, the authors hope to provide a stepping stone for new LIDAR researchers, students and scientific enthusiasts to begin investigating this ever expanding field of science and engineering, as well as bridge the discontinuity between textbooks and the latest advancements in LIDAR technology and experiments.