A hub is a small box that connects individual devices on network so that these devices can communicate with each other. Hub is an inexpensive device. It is commonly know as passive hub as it operates below physical layer of OSI model and works just as a connector. It is just a point where the signals coming from different network devices or terminals copied. A hub be thought of as the centre of a bicycle wheel where the spokes meet. Hub is also named as concentrator. Hub is placed in a network connecting in topology format.