A coil-on-plug system is an ignition system used in many modern vehicles. It replaces traditional ignition coils and spark plug wires with individual coils mounted directly on each spark plug. This design improves efficiency and reduces the chances of misfires, as each coil can deliver a precise spark at the right moment. These systems are often found in vehicles with internal combustion engines and contribute to better fuel economy and lower emissions. By eliminating the need for long wires, coil-on-plug systems also reduce electrical resistance, enhancing overall performance and reliability in the ignition process.