A computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources. Networks may be classified according to a wide variety of characteristics. A Computer network allows sharing of resources and information among interconnected devices. In the 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defence. It was the first computer network in the world. Development of the network began in 1969, based on designs developed during the 1960s. Computer networks can be used for numerous purposes; such as Facilitating Communications; Sharing Hardware; Sharing Files, Data, and Information; Sharing software.
Network classification: There are different categories that can be used to classify network. However, Computer networks can be classified according to the hardware and software technology that is used to interconnect them in the network, these are optical fibre, Ethernet, wireless LAN etc. Ethernet uses physical wiring to connect devices. Devices used for this sort of physical wiring include Hubs, Switches, Bridges, Routers etc. Wireless LAN technology is designed to connect devices without wiring while wired LAN technology is designed to connect devices with wiring. Networks are often classified according to their scale e.g. Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN) etc.
Network topology:
Computer networks may be classified according to the Network Topology upon which the network is based upon, such as Bus Network, Star Network, Ring Network, and Mesh Network. Network topology is the coordination by which devices in the network are arranged in their logical relations to one another.
