In addition to the hosts, LANs may use other devices to control physical access to the shared medium, extend the maximum reach of the LAN, switch traffic, and so on. Such hardware is in the form of NICs, repeaters, bridges, hubs, switches, routers, and gateways.
A repeater is a network device used to regenerate a signal. It operates within the physical layer of the OSI reference model and regenerate analog or digital signals that are distorted by transmission loss due to attenuation. A repeater does not make intelligent decision concerning forwarding packets. Repeater won't be disscused in detail.