A computer network connects computers together to share resources and exchange data. They can be connected by cables, satellites, or fiber optics. Examples include local area networks (LANs) and the Internet. LANs connect devices within a limited physical area like a building. Metropolitan area networks (MANs) connect devices over a larger area like a city. Wide area networks (WANs) connect computers and networks over large geographic areas, which may span continents. WANs link devices through various means and allow users to access the network via modem. Different network types have advantages and disadvantages related to security, speed, costs, and geographical reach. The Internet is a global network that connects smaller networks using the Internet Protocol.