Jump-starting a battery involves using a second battery to provide the necessary power to start a vehicle with a dead battery. This is typically done with jumper cables, which connect the positive and negative terminals of both batteries. The working battery supplies electricity to the dead battery, allowing the vehicle to start. Before jump-starting, ensure both vehicles are turned off. Connect the red cable to the positive terminal of the dead battery and then to the positive terminal of the working battery. Next, connect the black cable to the negative terminal of the working battery and attach the other end to a metal ground on the vehicle with the dead battery. This helps prevent sparks near the battery.