A vehicle's electrical system is a combination of the charging, starting, computer, ignition, and lighting systems. While the engine provides power to move the car, the electrical system powers most devices on the car. Without electricity, the starting motor couldn't crank the engine, the ignition system couldn't send sparks to the cylinder, the fuel-injection system wouldn't be able to provide fuel, and the lights and all electrical components of the vehicle wouldn't operate.
Some of the components of the electrical system are covered under a manufacturer's factory warranty. Others are covered under either the Federal or state emissions warranty, depending upon what state you reside in. After the factory warranty and emissions warranty expire, there are extended auto warranties available that will cover most components of the electrical system under the more comprehensive plans.