A computer network allows computing devices to exchange data through connections between nodes. There are different types of networks classified by geographic reach: local area networks (LANs) within a building or home; metropolitan area networks (MANs) spanning a city or campus; wide area networks (WANs) across countries or continents like the Internet; and personal area networks (PANs) communicating among devices within a few meters. LANs enable resource sharing and are fast but require wiring, while WANs can transmit data over long distances but are more expensive to install and maintain.