Computer network

A computer network is a collection of communicating <a href="/facts/Computer/SQe1aK05">computers</a> and other devices, such as printers and smart phones. Today almost all computers are connected to a computer network, such as the global <a href="/facts/Internet/Xw1rVvJU">Internet</a> or an embedded network such as those found in modern cars. Many applications have only limited functionality unless they are connected to a computer network. Early computers had very limited connections to other devices, but perhaps the first example of computer networking occurred in 1940 when <a href="/facts/George_Stibitz/M6pUBsqx">George Stibitz</a> connected a terminal at Dartmouth to his Complex Number Calculator at <a href="/facts/Bell_Labs/fKP5Gk0H">Bell Labs</a> in New York. 
In order to communicate, the computers and devices must be connected by a physical medium that supports transmission of information. A variety of technologies have been developed for the physical medium, including wired media like copper cables and <a href="/facts/Optical_fibers/5ruuIFbj">optical fibers</a> and wireless <a href="/facts/Radio-frequency/aWku7h4R">radio-frequency</a> media. The computers may be connected to the media in a variety of <a href="/facts/Network_topologies/rBYE0kke">network topologies</a>. In order to communicate over the network, computers use agreed-on rules, called <a href="/facts/Communication_protocol/5uady7cB">communication protocols</a>, over whatever medium is used. 
The computer network can include <a href="/facts/Personal_computer/koaYfNce">personal computers</a>, <a href="/facts/Server_(computing)/dEaYFD7r">servers</a>, <a href="/facts/Networking_hardware/ck0rIkXA">networking hardware</a>, or other specialized or general-purpose <a href="/facts/Host_(network)/HPNcFXHk">hosts</a>. They are identified by <a href="/facts/Network_address/W7RQVwBr">network addresses</a> and may have <a href="/facts/Hostname/WcLyMFKA">hostnames</a>. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the <a href="/facts/Internet_Protocol/Qq6VeEal">Internet Protocol</a>.
Computer networks may be classified by many criteria, including the <a href="/facts/Transmission_medium/yT1uXLmq">transmission medium</a> used to carry signals, <a href="/facts/Bandwidth_(computing)/lY6Tb4gX">bandwidth</a>, <a href="/facts/Communications_protocol/5uady7cB">communications protocols</a> to organize <a href="/facts/Network_traffic/sdUtmrxM">network traffic</a>, the network size, the topology, <a href="/facts/Network_traffic_control/98KPazFF">traffic control</a> mechanisms, and organizational intent.
Computer networks support many <a href="/facts/Application_software/YQuj7Kog">applications</a> and <a href="/facts/Network_service/GdLvd2ml">services</a>, such as access to the <a href="/facts/World_Wide_Web/wvnTrWFq">World Wide Web</a>, <a href="/facts/Digital_video/xsn9omqG">digital video</a> and <a href="/facts/Digital_audio/PgugcLAI">audio</a>, shared use of <a href="/facts/File_server/4SFrAdHY">application and storage servers</a>, <a href="/facts/Printer_(computing)/PnDF2QuF">printers</a> and <a href="/facts/Fax_machine/EBvf1cHA">fax machines</a>, and use of email and instant messaging applications.

Computer network open-in-new

Computer network