(1) In a system or communications network, a point at which data can either enter or leave.
(2) The point at which one node in a message flow is connected to another node. Terminals can be connected to control the route that a message takes, dependent on the outcome of the operation that is performed on that message by the node.
(3) In data communication, a device, usually equipped with a keyboard and display device, capable of sending and receiving information.