A power strip (also known as an extension block, power board, power bar, plug board, trailer lead, and by many other variations) is a block of electrical sockets that attaches to the end of a flexible cable (typically with a mains plug on the other end), allowing multiple electrical devices to be powered from a single electrical socket. Power strips are often used when many electrical devices are in proximity, such as for audio/video and computer systems. Power strips often include a circuit breaker to interrupt the flow of electric current in case of an overload or a short circuit. Some power bars provide protection against electrical power surges