Network – any and all connections between computing devices. If you think of human anatomy, the network is like the intricate nervous system that takes messages from the brain to the rest of the body and takes feedback from the body back to the brain. It is made up of a series of interconnected nodes that are communicating with one other via predetermined protocols, such as Transmission Control protocol (TCP) / Internet Protocol (IP), that dictate how information will be transported and handled by the devices (switches, routers, security gateways) that forward the traffic from one node to another.
Networks can be characterized based on the proximity of all the nodes they connect, for example, local area network (LAN) or wide area networks (WANs), or whether they are public or private. They can also be characterized based on the type of traffic they transport, such as voice or data, e.g. wireless local area network (wLANs), or whether they are made up of physical or virtual devices, such as virtual local area networks (vLANs). They can also be described based on the way in which they transport communications; for example packet-switched versus circuit switched networks.