Batteries are devices that store and release electrical energy through electrochemical reactions. They consist of one or more electrochemical cells, each containing two electrodes (a positive cathode and a negative anode) and an electrolyte that allows ions to move between the electrodes. When a battery is connected to an electrical circuit, a chemical reaction occurs, generating a flow of electrons (electricity) to power devices. Batteries are widely used to power various devices, from portable electronics to vehicles.