A computer network is a telecommunications network that allows two or more computers to exchange information.
A network is made up of two or more network nodes. Any networkable device such as a computer, printer, server, or a piece of network hardware can be a node. Network nodes are connected either by physical cabling or wireless signals such as WiFi.
Computer networks first began to appear in the 1950s. Examples of the uses of the earliest computer networks include military radar systems, commercial airline reservation systems, and governmental and educational research networks. Later networks, such as ARPANET and NSFNET were created to speed development of the technologies necessary to power what we now know today as the Internet.
Every network depends on three key components in order to function:
- Physical infrastructure: In order for a network to exist and function, it must include the necessary hardware and cabling to connect the different network nodes and transfer information between nodes.
- Communication protocols: In order for different nodes to locate each other and communicate, an addressing system and a set of communication protocols must be established.
- Software: If users are to make use of network resources, they must have suitable software available to interact with network resources.
The Internet is the best-known computer network and is actually comprised of many smaller networks which have been networked together to form a massive worldwide grid. This massive worldwide network is the physical infrastructure that Internet communications travel over. The Internet protocol suite, TCP/IP, defines the addressing system and communication protocols used to locate nodes over the Internet and transfer information. The software used to send information over the Internet varies depending on the communication protocol and type of content involved. A few common examples include web browsers (which communicate over HTTP), Usenet newsreaders (which communicate over NNTP), and VoIP applications (which make use of a few different protocols).
Frequently Asked Questions
How can multiple users communicate over a network at the same time?
The key to enabling multiple users to communicate over a network simultaneously is the use of information packets. Information sent over a packet-switched network is broken into tiny pieces and stamped with an origination and destination address. The packets are then sent over the network to the destination. Since each packet is addressed, it is not necessary to establish and maintain a constant open connection to the destination while the information is in transit. Instead, information from multiple sources can be allowed to stream simultaneously while network hardware reads the addresses on each packet and relays the packets to their intended destination.
The alternative to a packet-switched network is a circuit-switched network in which a network connection must be constantly maintained while information passes from a sender to a recipient.
Are all networks publicly accessible like the Internet?
Networks may be either publicly accessible or private. Private networks may use public infrastructure, but protect access by using encryption and tunneling technologies such as VPNs. One common type of private network is an intranet. Intranets are common among large organizations and are used to provide access to organizational resources such as data and software.
Networks can also be described based on geographic scale. Local area networks (LAN) are confined to a small geographic area, typically a single building. Wide area networks (WAN) are usually comprised of multiple LANs which have been networked together – often using VPN technologies to maintain network privacy. The Internet is itself an example of a WAN, albeit one with a generally open architecture to allow the free exchange of information.