A light-dependent resistor (LDR) is a type of resistor that changes its resistance based on the amount of light it receives. When light levels are high, the resistance decreases, allowing more current to flow through. Conversely, in low light conditions, the resistance increases, reducing the current. LDRs are commonly made from semiconductor materials, which are sensitive to light. LDRs are widely used in various applications, such as automatic streetlights, solar garden lights, and light-sensitive alarms. They help devices respond to changes in light, making them useful for energy-saving solutions and enhancing safety in outdoor environments.