A network is a collection of devices and end systems.
Networks consist of computers, servers, and network devices, such as switches and routers, that can communicate with each other.
Figure 1-1 shows the four major categories of physical components on a network:
Personal computers (PCs): Send and receive data and are the endpoints of the network.
Interconnections: Are the components that provide a means for data to travel across the network. This includes network interface cards (NIC), network media, and connectors.
Switches: Provide network access for the PCs.
Routers: Interconnect networks.
Figure 1-1. Network Components