An accumulator is a device or component that stores energy for later use. It can be found in various systems, such as hydraulic systems, where it helps maintain pressure and smooth operation. Accumulators can also refer to electronic circuits that collect and store electrical charge. In programming, an accumulator is a variable that keeps a running total or aggregate of values during a computation. For example, in a loop, an accumulator can sum numbers or concatenate strings, making it a useful tool for data processing tasks.