This document describes a smart street light system based on Arduino that can automatically control street lights. The system uses infrared sensors and a light dependent resistor to detect movement of vehicles or pedestrians and the level of ambient light. When motion is detected by the infrared sensors or it becomes dark, the Arduino microcontroller powers the LED street lights. This automatic control can save power by only illumining the lights when needed rather than keeping them on all the time. The system aims to provide energy efficient and adaptive street lighting using new technologies like sensors and microcontrollers.