In the context of GPS data processing, "snap to road" means aligning a GPS point to the nearest point on a road network. This process involves matching the GPS point to the most likely road segment based on various factors such as the direction of travel, speed limits, and other contextual information. By snapping the GPS point to the nearest road segment, it becomes easier to analyze and visualize the corresponding route and estimate factors such as travel time, distance, and speed. This process is typically done using a map-matching algorithm, such as the one used by the Geoapify Map Matching API.