Routers enable public networks to be used between LAns which can reduce costs. Routers provide, flexibility. The facilities on most LANs are very powerful. Most organisations do not wish to have small separate computing facilities. They usually want to extend facilities over a wider area so that groups can work without having to be located.
Bridges are specialised devices that allow two or more LANs to be connected.
The bridge is the more basic device and can only connect LANs of the same type. The bridge is a connection between two networks which make use of the same logical protocols, but might use different physical protocols such as ring and a bus network. Bridges will pass packets of information from one LAN to the other which could be situated in the next building. Advantages of Bridges are that they enable connection of different types of LAN networks together. They can improve security of the network.