Computer network

Overview

A computer network is a set of computers and other devices that are connected to share resources and communicate with one another. Networks can be as small as two computers linked in a home office or as large as a global system like the Internet. They are fundamental to modern computing, enabling data transfer, resource sharing, and collaborative work.

History

The earliest computer networks emerged in the 1960s, with the ARPANET (funded by the U.S. Department of Defense) being a key precursor to the modern Internet. In the 1970s, protocols such as TCP/IP were developed to standardize communication. The 1980s saw the rise of local area networks (LANs) using technologies like Ethernet, while the 1990s brought widespread adoption of the Internet and wireless networking. Today, networks range from small home setups to massive data center fabrics.

Components

Nodes – devices such as computers, servers, printers, and routers that participate in the network.
Links – physical (e.g., Ethernet cables, fiber optics) or wireless (e.g., Wi‑Fi, cellular) connections.
**Network interfaces** – hardware (network interface cards) and software (drivers, protocols) that enable a device to connect.
Switches and routers – devices that direct data traffic within and between networks.
Protocols – sets of rules (e.g., IP, HTTP, DNS) that govern how data is transmitted and received.

Types

Networks are classified by scale and purpose:

Personal Area Network (PAN) – connecting devices near a single person, e.g., Bluetooth.
Local Area Network (LAN) – a network within a limited area, such as an office or home.
Wide Area Network (WAN) – spanning large geographic distances, e.g., the Internet.
Metropolitan Area Network (MAN) – covering a city or campus.
Virtual Private Network (VPN) – a secure tunnel over a public network.

Characteristics

Important characteristics include performance (throughput, latency), reliability, security, and scalability. Networks can be designed as client‑server (centralized resources) or peer‑to‑peer (decentralized). Management often involves monitoring traffic, configuring devices, and enforcing access controls.