A photoresistor, also known as a light-dependent resistor (LDR), is an electronic component that changes its resistance based on the amount of light it receives. When exposed to light, the resistance decreases, allowing more current to flow through the circuit. Conversely, in darkness, the resistance increases, reducing the current. This property makes photoresistors useful in various applications, such as light sensors and automatic lighting systems. Photoresistors are commonly made from semiconductor materials, which are sensitive to light. They are often used in devices like solar garden lights, streetlights, and camera exposure meters. By detecting changes in light levels, photoresistors help automate functions and improve energy efficiency.