A computer network connects multiple computers and devices to allow communication and sharing of resources. There are different types of networks including local area networks (LANs) within a single building, metropolitan area networks (MANs) within a city, and wide area networks (WANs) across large distances like countries. Common network topologies include bus, ring, star, tree and mesh configurations. Computer networks enable file sharing, printer sharing, collaboration, remote access, data protection, and centralized administration.