Depth perception is essential for applications like autonomous vehicles, robotics, and automation. Stereo vision camera provides one way for the above purpose but has a limited range. Radar has also been used for depth sensing but does not provide precise resolution. LiDAR (Light Detection and Ranging) provides a three-dimensional view of a scene with much higher resolution as compared to Radar and has a much larger range than Stereo vision camera. In this paper, we present a complete overview of LiDAR, which includes basic principles, data acquisition methods, a comparative study among different sensors. An analysis of variation in data rate and the number of points for different return modes with the varying number of channels is also presented. © 2020 IEEE.