Runway threshold marking refers to the visual indicators located at the beginning of a runway, which help pilots identify the point where the runway officially starts. These markings are typically painted in white and consist of a series of stripes that extend across the width of the runway. They are crucial for safe landings and takeoffs, especially in low visibility conditions. The markings also indicate the usable length of the runway for aircraft operations. When a runway is closed or not fully usable, the threshold markings may be altered or supplemented with additional signs to inform pilots of the current status.