We see the network as the system that connects computers, printers and other IT equipment in your office to make use of the internet. Think of the firewall, the fixed network and the Wi-Fi network.
According to Wikipedia: "A computer network is a system for communication between two or more computers." The communication is done via network cables or via a wireless network. In network topology, physical and logical topologies are distinguished. One speaks of a LAN in the case of local area cabling to which computers within one building or campus are connected, and a WAN when connections over greater distances are involved.