A battery’s power comes from the tendency of electric charge to migrate between different substances. It is the power that Italian scientist Alessandro Volta sought to tap into when he built the first battery at the end of 1799.
Although different designs exist, the basic structure has remained the same ever since. Every battery has two electrodes. One, the anode, wants to give electrons (which carry a negative electric charge) to the other, the cathode. Connect the two through a circuit, and electrons will flow and carry out work—say, lighting a bulb or brushing your teeth.