A computer network connects multiple devices through communication channels, allowing users to share resources and communicate. There are advantages like sharing resources and communication, but also drawbacks such as costs and security risks. Networks can be local area networks (LANs) connecting devices within a building, metropolitan area networks (MANs) spanning a larger region, or wide area networks (WANs) connecting multiple LANs over long distances. Components include media like cables and wireless, as well as devices like network interface cards, bridges, switches, and routers that help direct data traffic.