An opto-isolator, 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 photodetector, such as a photodiode or phototransistor, housed together. When an electrical signal activates the LED, it emits light, which is then detected by the photodetector, allowing the signal to pass without direct electrical connection. Opto-isolators are commonly used in various applications to provide electrical isolation between different parts of a circuit. This isolation helps protect sensitive components from high voltages or noise, ensuring reliable operation in devices like power supplies, microcontrollers, and communication systems.