Photogrammetry and GIS professional frequently facing one very common question "What is Lidar ?". A detailed discussion is given in this post.These information are very helpful to understand "What is Lidar ?"
Lidar stands for Light Detection and Ranging and is very similar to the better known Radar. LIDAR is a better choice than radar, because it has a greater ability to reflect images, making more objects visible. LIDAR uses waves ten to one hundred thousand times shorter than radar waves, which means that it is able to collect much more data.