Which term best describes the purpose of PAPI lights?

PAPI lights, which stand for Precision Approach Path Indicator, are designed to provide visual glide slope guidance to pilots during their approach to landing. These lights are typically located to the side of the runway and use a system of colored lights to indicate whether the aircraft is on the correct glide path to the runway. When the aircraft is on the ideal approach angle, the lights will display a specific combination of red and white colors, guiding the pilot to maintain the correct altitude and descent rate for a safe landing. This function is crucial for ensuring that pilots can effectively align their approach, particularly in varying visibility conditions, making PAPI lights an essential part of runway approach aids.