Before revision: Its largest use was the contact breaker or "points" in the distributor of the ignition system of gasoline engines, which served to break ignition coil which created the sparks in the spark plugs.
After revision: Its largest use was the contact breaker or "points" in the distributor of the ignition system of gasoline engines, which served to periodically interrupt the current to the ignition coil producing high voltage pulses which create sparks in the spark plugs.