What is a computer network?


Networks are made up of network nodes (endpoints, switches and routers) which use interconnections to communicate with each other and move data from one device to another. Network components may be structured in a number of different topologies depending on the size and purpose of the network. For example a home network will look very different to an enterprise network which could span multiple offices across the globe.

To make it easier to build networks using many components, potentially from many different manufacturers we split it into layers. The lowest layer includes the medium used to transmit ones and zeros across physical space – for example an Ethernet cable or some form of wireless technology. The highest layer includes applications such as a web browser which turns the data transmitted across the network into something useful. We use two models to represent networks, the Open Systems Interconnection (OSI) model and the TCP/IP or Internet Protocol Suite model.

Each layer will implement one or more protocols as a means of communication. A protocol is simply a set of rules which all parties follow in order to understand each other. For example, let's look at a protocol analogy for social etiquette:

Free flow conversation is now free to happen until either party decides to close the conversation:

Devices on a network, like the people in our analogy, will only communicate successfully if they both adhere to the same protocol.

The core protocols in use today, including the Transmission Control Protocol (TCP) and the Internet Protocol (IP), date back to research carried out for the US Department of Defence and at US universities in the 1970s and 1980s.


Test your knowledge with these questions.

LAN stands for Local Area Network. A LAN connects devices in a relatively small physical area such as a room or building.

WAN stands for Wide Area Network. A WAN connects devices over long distances.

In computer networking, a protocol is a set of rules which define the language devices use to communicate with each other.

Two commonly used models in computer networking are the OSI 7 Layer Reference Model and the TCP/IP model.

Local Area Network

Local Area Network (LAN)

Wide Area Network (WAN)

Wide Area Network

Other Lessons

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Summary of the TCP/IP Model




This lesson is part of the following courses.

Computer Networking Foundations