What is lidar and how is it used in autonomous vehicles?

Lidar (Light Detection and Ranging) uses laser pulses to create detailed 3D maps of the environment. It measures distance by timing how long light takes to return after hitting objects, scanning thousands of points per second to create a point cloud. Types include mechanical (rotating mirror), solid-state (no moving parts), and MEMS-based. Advantages include high accuracy, precise depth information, and detailed 3D perception. Challenges include cost (though decreasing), performance in adverse weather (snow, fog), and sensitivity to dirt. Lidar is considered essential for L4/L5 autonomy by many developers due to its precision, though some approaches use camera-only solutions.