internet service provider and network backbone

4. Few ISPs of Nepal Country :

5.  A backbone is the part of the computer network
infrastructure that interconnects different networks and
provides a path for exchange of data between these
different networks.
 A backbone may interconnect different local area
networks in offices, campuses or buildings.
 When several local area networks (LAN) are being
interconnected over a considerable area, the result is a
wide area network (WAN), or metropolitan area network
(MAN) if it happens to serve the whole city.
Network backbone

6. Network backbone