What Is a Computer Network?

A computer network is two or more connected devices that exchange data and share resources over wired or wireless links. A computer network connects devices such as computers, servers, phones, and printers through transmission media and networking hardware so each device reaches the others. The Institute of Electrical and Electronics Engineers (IEEE) and the Internet Engineering Task Force (IETF) define the standards that let these devices communicate.

This article defines a computer network, then explains the components that build one, the network types by geographic scale, the difference between wired and wireless networks, the client-server and peer-to-peer models, and the functions a network performs. Each section states one part of the topic and how it relates to the connected devices and shared resources at the center of the definition. The result is a complete account of what a computer network is, what it is made of, and how its forms differ by size, medium, and organization.

What Is a Computer Network?

A computer network is a system of two or more connected devices that exchange data and share resources through transmission media governed by communication protocols. A computer network links devices, called nodes, with physical or wireless connections, and the nodes follow agreed rules to send and receive information. The defining traits of a computer network are listed below:

• Two or more connected devices form the minimum, since a single isolated device is not a network.
• A transmission medium carries the data, using cables, radio waves, or fiber-optic light.
• Shared resources include files, printers, internet access, and applications reached across the connection.
• Communication protocols set the rules each device follows to format, address, and deliver data.

A computer network depends on agreed rules that govern data exchange, defined in the explanation of what a network protocol is. The arrangement of the nodes and their links forms the network layout, set out in the guide to network topologies.

What Are the Components of a Computer Network?

A computer network is built from nodes, links, network interface cards, switches, and routers, each performing one function in moving data between devices. A network combines end devices that produce and consume data with hardware that connects and directs the traffic between them. The components of a computer network are listed below:

• Nodes are the end devices, such as computers, servers, printers, and phones, that send and receive data.
• Links are the transmission media, including copper cable, fiber-optic cable, and wireless radio channels.
• Network interface cards connect each device to the medium and hold the device’s hardware address.
• Switches connect devices within one network and forward data to the correct destination port.
• Routers connect separate networks and forward data between them using network addresses.

A network interface card carries a unique hardware identifier, detailed in the description of a MAC address. A router forwards traffic between networks using logical addresses, which the overview of an IP address defines.

What Are the Types of Computer Networks by Scale?

Computer networks are classified by geographic scale into four main types: personal area network (PAN), local area network (LAN), metropolitan area network (MAN), and wide area network (WAN). A network type describes the area it covers and the number of devices it links, from a single person’s devices to networks spanning countries. The network types by scale are listed below:

• A personal area network (PAN) connects one person’s devices within a few meters, often over Bluetooth.
• A local area network (LAN) connects devices within one building or site, such as a home or office.
• A metropolitan area network (MAN) connects sites across a city, larger than a LAN and smaller than a WAN.
• A wide area network (WAN) connects networks across regions or countries, with the internet as the largest example.

A local area network, a metropolitan area network, and a wide area network differ in coverage, ownership, and speed, compared in detail in the comparison of LAN, WAN, and MAN. The wide area network that links networks worldwide is the subject of the overview of what the internet is.

How Do Wired and Wireless Networks Differ?

Wired networks transmit data through physical cables, while wireless networks transmit data through radio waves, which sets their differences in speed, range, and mobility. A wired network uses copper or fiber-optic cable for a stable connection, whereas a wireless network uses radio frequencies defined by the IEEE 802.11 standard for mobility. The differences between wired and wireless networks are listed below:

• Wired connections use Ethernet cable, providing stable speed and low interference over fixed paths.
• Wireless connections use radio waves under IEEE 802.11, providing mobility without physical cables.
• Wired networks resist interference and offer consistent latency for stationary devices.
• Wireless networks trade some speed and stability for the freedom to move within signal range.

The IEEE 802.3 standard defines wired Ethernet, while the IEEE 802.11 family defines wireless local area networking, commonly called Wi-Fi. A wired network and a wireless network can coexist in one local area network, with devices choosing the medium that fits their location and need for mobility.

What Is the Difference Between Client-Server and Peer-to-Peer Networks?

A client-server network centralizes resources on dedicated servers that clients request, while a peer-to-peer network lets each device act as both a provider and a consumer of resources. A client-server model assigns roles, with servers holding data and services and clients requesting them, whereas a peer-to-peer model treats every device as an equal. The two models differ in these traits:

• A client-server network stores resources on central servers that respond to client requests.
• A peer-to-peer network shares resources directly between equal devices with no central server.
• A client-server network scales and secures more easily through centralized control.
• A peer-to-peer network costs less to set up but distributes management across every device.

A client-server network suits organizations that centralize files, email, and applications, while a peer-to-peer network suits small groups sharing resources directly. Both models rely on the same underlying protocols, including the suite explained in the overview of TCP/IP.

What Does a Computer Network Enable?

A computer network enables resource sharing, communication, centralized data storage, and internet access across connected devices. A network removes the need to duplicate resources on every device, letting users share hardware, files, and services through the connection. The functions a computer network enables are listed below:

• Resource sharing lets multiple devices use one printer, storage drive, or internet connection.
• Communication carries email, messaging, voice, and video between connected users.
• Centralized storage keeps files on a server that authorized devices reach from any node.
• Internet access connects the local network to the global wide area network through a router.

A computer network turns isolated devices into a system that shares data and services, the basis of every connected application. The path data follows from one device to another across networks is traced in the explanation of how data travels on the internet.

What Network Devices Connect and Direct Traffic?

Network devices that connect and direct traffic include hubs, switches, routers, access points, and modems, each operating at a defined layer to move data toward its destination. A network device either connects nodes within one network or forwards data between networks, and the device type determines how it directs traffic. The main network devices are listed below:

• A hub connects devices and repeats every signal to all ports, with no traffic direction.
• A switch connects devices within one network and forwards data only to the destination port.
• A router connects separate networks and forwards packets between them using logical addresses.
• A wireless access point connects wireless devices to a wired network over IEEE 802.11 radio.
• A modem converts a network signal between the local network and an internet service provider’s line.

A switch directs traffic by hardware address within a local area network, while a router directs traffic by logical address between networks, using the addressing in the overview of an IP address. The layout these devices form across a network is set out in the guide to network topologies.

How Is Network Performance Measured?

Network performance is measured by bandwidth, throughput, latency, and packet loss, which describe how much data a network carries and how quickly it arrives. A performance metric quantifies one aspect of the connection, from capacity to delay, and together the metrics describe the quality of a network link. The main performance metrics are listed below:

• Bandwidth is the maximum data rate a link can carry, measured in bits per second.
• Throughput is the actual data rate achieved, which can fall below the rated bandwidth.
• Latency is the delay a packet takes to travel from source to destination, measured in milliseconds.
• Packet loss is the percentage of packets that fail to reach the destination and require retransmission.

Bandwidth sets the ceiling on data rate, while throughput, latency, and packet loss describe the real conditions a connection delivers. A wired network typically shows lower latency and packet loss than a wireless network, since radio signals face more interference than cabled connections.

Key Takeaways

• A computer network is two or more connected devices that exchange data and share resources.
• Core components include nodes, links, network interface cards, switches, and routers.
• Network types by scale are PAN, LAN, MAN, and WAN, from personal range to global reach.
• Wired networks use cables for stability, while wireless networks use radio waves for mobility.
• Client-server networks centralize resources, while peer-to-peer networks treat devices as equals.
• A network enables resource sharing, communication, centralized storage, and internet access.

Last Thoughts on Computer Networks

A computer network connects two or more devices so they exchange data and share resources through transmission media and networking hardware. The components, nodes, links, network interface cards, switches, and routers, work together under communication protocols to move data to the correct destination.

Network types by scale, wired and wireless media, and client-server and peer-to-peer models describe how networks differ in size, medium, and organization, while resource sharing and communication explain what they accomplish. Readers can continue with the guide to network topologies, the explanation of network protocols, the comparison of LAN, WAN, and MAN, or the guide to how networks work for related topics.