An IR Sensor Line Follower is a simple and very popular sensor system used in robotics to detect and follow a line (usually black line on a white surface, or vice versa). It works by using Infrared (IR) light to detect the difference between reflective and non-reflective surfaces. 🔹 Working Principle The sensor has two main parts: IR LED (Transmitter) → emits infrared light onto the surface. Photodiode/Phototransistor (Receiver) → detects the reflected IR light. White surface (reflective) → reflects most of the IR light back, so the receiver detects it → gives HIGH signal. Black surface (absorptive) → absorbs IR light, very little reflection → receiver detects nothing → gives LOW signal. Thus, by arranging multiple IR sensors, a robot can “see” the line and adjust its movement. 🔹 Typical Module Pins VCC → 3.3V – 5V GND → Ground OUT → Digital output (HIGH/LOW depending on surface) Some advanced modules also have analog output and sensitivity adjustment potentiometer. 🔹 How It Works in a Line Follower Robot Two or more IR sensors are placed at the bottom of the robot. If the left sensor is on black and the right sensor is on white, the robot knows it has to turn left. If the right sensor is on black and the left is on white, it turns right. If both are on white, it keeps moving forward. If both are on black, it may stop or decide it has reached a junction. 🔹 Applications Line follower robots (education & competitions). Automated guided vehicles (AGVs) in industries. Object detection and counting systems. Black/white surface differentiation. 🔹 Advantages Low cost and easy to use. Reliable for simple robotics projects. Works well on contrasting surfaces. ⚡ Example with Arduino: Connect VCC → 5V, GND → GND, OUT → digital pin. The Arduino reads HIGH (1) on white surface, and LOW (0) on black surface.