Fence: In a physical security context, a fence is a barrier used to enclose or secure an area, typically made from posts connected by boards, wire, or rails, and is designed to prevent intrusion or escape. In computing, fencing can refer to a network security measure that isolates a node or system to protect the rest of the network when a security issue is detected. It also refers to a method of multiprocessing to prevent data corruption by coordinating exclusive access to shared resources.