What is loop in loop out in reference to electricity?

Loop in loop out refers to a wiring method commonly used in electrical installations, particularly for lighting circuits. It allows multiple light fixtures to be connected in a series by creating a continuous circuit, where the power enters a fixture (loop in) and then exits to the next fixture (loop out). This method simplifies wiring and reduces the number of cables needed, making installations more efficient while ensuring all lights can still be operated from a single switch.