Some moldmakers distinguish the sprue, the gate, and the runner. The sprue is a large-diameter channel through which plastic flows, usually around the edges of the part or along straight lines. The runner is a smaller channel from the sprue to the individual part. An analogy may be found in a water system that employs a water main (sprue) and smaller pipes (runners) to individual houses. The gate is the location at which the molten plastic enters the mold cavity and is often evidenced by a small nub or projection (the "gate mark") on the molded piece.