Definition - What does Backbone mean?
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.
Techopedia explains Backbone
On a large scale, a backbone is a set of pathways to which other large networks connect for long distance communication. Various networking technologies work together as connection points or nodes, and are connected by different mediums for transporting data like optical fiber, traditional copper and even wireless technology like microwave and satellites. The traditional notion of a backbone is a bundle of wires, which serves the multiple networks as the main super highway for data. The idea remains the same, but the execution has become more diverse. Of course the capacity of the backbone is supposed to be greater than that of the networks it serves.