A network is a collection of interconnected entities that can communicate or exchange resources according to defined rules and through some form of connection. In computing, a network generally consists of devices or systems connected so that they can exchange data, share services or coordinate activity. The participating entities can include computers, servers, smartphones, printers, storage systems, routers, switches, sensors, industrial controllers and virtual machines.
A network does not necessarily mean the public Internet, nor does it necessarily require physical cables. Connections can use copper, fibre-optic cable, radio, microwave, satellite or virtual networking mechanisms implemented in software. The fundamental idea is interconnection combined with communication. A network can be extremely small, such as two directly connected devices, or extremely large, such as the global collection of interconnected networks that forms the Internet. The term is therefore broader than “computer network”, because networks can also exist in biological, social, transportation, electrical and other domains, although computer networking specifically concerns digitally communicating systems.
A computer network requires more than simply having multiple devices physically connected. The devices need agreed rules and mechanisms for addressing, transmitting, receiving and interpreting information. These rules are commonly implemented through networking protocols and standards. Protocols determine matters such as how data is formatted, how devices identify destinations, how communication sessions are established, how errors are handled and how information is routed. At different layers of a networking architecture, different protocols solve different problems.
Ethernet and Wi-Fi provide local link technologies, IP provides logical addressing and packet delivery across interconnected networks, TCP provides reliable ordered byte-stream transport, UDP provides connectionless datagram transport, and application protocols such as HTTP, DNS, SMTP and SSH define higher-level services. A network therefore consists of interacting components whose behaviour is governed by multiple layers of technology rather than by a single universal protocol.
Network topology describes how network components are arranged and interconnected. Common logical or physical topologies include bus, star, ring, mesh and tree arrangements. In a star topology, individual devices connect to a central switch or other central component, which is common in modern Ethernet LANs. A mesh topology provides multiple paths between nodes and can improve redundancy and resilience, although it generally requires additional links or routing complexity.
Physical and logical topology can differ: devices may be physically connected in one arrangement while traffic flows according to a different logical structure. Network architecture also involves endpoints and intermediary devices. Endpoints generate or consume application data, whereas switches, routers, firewalls, gateways and access points primarily facilitate communication between endpoints or networks. Modern networks can additionally contain virtual switches, virtual routers and software-defined components that have no direct one-to-one correspondence with physical hardware.
Addressing is fundamental because a network needs a way to distinguish destinations. At the Internet Protocol layer, IPv4 uses 32-bit addresses and IPv6 uses 128-bit addresses. An IP address identifies a network interface or endpoint within the addressing architecture, while a MAC address is associated with a network interface at the data-link layer in technologies such as Ethernet. These addresses serve different purposes and should not be treated as interchangeable identifiers.
Domain names provide human-readable names that can be translated into IP addresses through the Domain Name System. Routing determines how packets move between different IP networks, while switching generally forwards frames within a local Layer 2 network based on link-layer information. Network Address Translation can also alter the apparent addressing of traffic between private and public addressing domains. These mechanisms allow large networks to operate without requiring every device to share a single flat addressing space.
Networks can be classified according to their geographical scope, ownership, architecture and purpose. A personal area network may connect devices around one person, while a local area network normally covers a home, office, building or similarly limited site. A metropolitan area network traditionally covers a city or metropolitan region, while a wide area network connects geographically separated sites across large distances. The Internet is a global internetwork rather than simply a very large LAN.
Enterprise networks may combine multiple LANs, WAN links, wireless networks, data-centre fabrics, cloud networks and remote-access systems. Public and private networks also differ in ownership and accessibility. A private corporate network may restrict access to authorised users, while a public network can be accessible to a much broader population. These classifications overlap because one organisation can operate networks of several scopes simultaneously.
Network communication can be evaluated in terms of characteristics such as bandwidth, latency, throughput, reliability, availability, packet loss, jitter and scalability. Bandwidth describes the theoretical or configured capacity of a communication link, whereas throughput describes the amount of useful data actually transferred over time. Latency represents delay between points in communication and can be influenced by propagation, processing, queuing and transmission factors. Jitter describes variation in packet delay and is particularly relevant to real-time voice and video.
Reliability concerns whether communication remains operational and whether data is delivered correctly, while availability concerns whether the service can be accessed when required. A network designed for high-volume data transfer may prioritise different characteristics from one designed for low-latency industrial control or real-time communications. Network engineering therefore involves balancing physical, protocol, economic, operational and security constraints.
Network security adds mechanisms intended to control who can communicate, what they can access and how traffic is protected. Firewalls filter traffic according to configured policies, network access control systems can restrict device participation, authentication systems verify users or devices, and encryption protocols such as TLS protect application traffic. Intrusion detection and prevention systems analyse traffic for suspicious patterns, while segmentation divides a network into security or operational zones.
Virtual LANs can separate broadcast domains logically, and routing or firewall policies can regulate communication between those segments. Security is not inherent in the existence of a network; an interconnected system can introduce additional attack paths if it is poorly configured. Conversely, network connectivity enables essential functions such as remote administration, distributed applications, cloud services, collaboration and resource sharing. Network design therefore involves both connectivity requirements and controls over that connectivity.
A network is ultimately an organised system for enabling communication and resource exchange between interconnected participants. Its defining elements include nodes or endpoints, communication links, addressing, protocols and mechanisms for forwarding or delivering information. Networks can be wired or wireless, physical or virtual, private or public, small or global, and dedicated to general-purpose computing or specialised functions. Computer networks form the foundation for the Internet, cloud computing, distributed applications, modern telecommunications, enterprise systems and connected devices.
The term should not be confused with the Internet itself: the Internet is a particular global system of interconnected IP networks, whereas “network” is a general concept that includes countless independent networks. Understanding networks therefore requires considering both the physical connections that carry signals and the logical protocols, addressing systems and policies that determine how those connections are used.
