An optoisolator, also known as an optocoupler, is an electronic component that transfers electrical signals using light waves. It typically consists of a light-emitting diode (LED) and a photosensitive device, such as a photodiode or phototransistor, housed together. When an electrical signal activates the LED, it emits light, which is detected by the photosensitive device, allowing the signal to pass through while keeping the input and output electrically isolated. This isolation is crucial in protecting sensitive components from high voltages or noise in a circuit. Optoisolators are commonly used in various applications, including power supplies, signal processing, and data communication, ensuring safe and reliable operation in electronic systems.