An AC adapter or AC/DC adapter (also called a wall charger, power adapter, or informally wall wart, or, in some configurations, power brick) is a type of external power supply, often enclosed in a case similar to an AC plug. AC adapters deliver electric power to devices that lack internal components to draw voltage and power from mains power themselves. The internal circuitry of an external power supply is often very similar to the design that would be used for a built-in or internal supply.
When used with battery-powered equipment, adapters typically charge the battery as well as powering the equipment.