What Is a Computer Network? Basics, Devices, and How It All Connects

The author, a wireless network engineer at Ubiquiti Shanghai with a Cisco CCIE R&S certification, shares practical knowledge to help non‑technical readers demystify networking, covering what a network is, how messages travel, the roles of common devices, and how to build a basic network.

What Is a “Network”?

In today’s world, networks are inseparable from daily life; any interruption or slowdown affects us. A computer network is simply a collection of computers connected together. Below is a simple network topology diagram.

The diagram shows switches, routers, APs, and terminals such as computers and phones. Switches, routers, and APs form the communication backbone, while cables (Ethernet, fiber) provide the physical links. These devices can be considered embedded computers.

How Does a Home Network Work?

In a typical home, the router forwards all device requests to the ISP’s network and the Internet. When many devices need connections, a switch expands the number of available ports.

As demand grew, wired solutions alone became insufficient, leading to the use of APs and wireless terminals. An AP functions like a wireless switch, connecting wireless devices via radio waves. A consumer Wi‑Fi router combines a router, switch, and AP in one unit, featuring a WAN port, multiple LAN ports, and antennas for wireless clients.

What Do LAN, MAN, and WAN Mean?

Computer networks are classified as LAN (Local Area Network), MAN (Metropolitan Area Network), and WAN (Wide Area Network). A LAN typically covers a home or office, a MAN spans a city, and a WAN connects to the broader Internet via the ISP.

Data Communication and Resource Sharing

The primary function of a computer network is data communication, enabling the exchange of information, software, and hardware resources. This includes sharing files, streaming media, accessing cloud services, and more.

Transmission Media and Network Devices

Beyond devices and terminals, physical media—cables and wireless signals—connect senders and receivers. Common media include coaxial cable, twisted‑pair Ethernet cable, fiber optics, and electromagnetic waves.

Cable Types

Coaxial cable was used in early Ethernet (up to 10 Mbps). Modern networks rely on twisted‑pair Ethernet cables, available in categories 5, 5e, 6, 6a, and 7, each supporting higher speeds over distances up to 100 m.

Fiber Optics: Ideal for Long‑Distance Transmission

Fiber optics, made of glass or plastic, offer low attenuation, high speed, and long reach, making them suitable for backbone connections. Single‑mode fiber can transmit over 20‑120 km, while multimode fiber serves shorter distances (up to 2 km) within LANs.

Radio Waves: Extending Beyond Cables

Wireless networks use radio waves (typically 2.4 GHz and 5 GHz) to transmit data, overcoming the physical limitations of cables and enabling mobility.

Routers, Switches, and Access Points

Routers connect different networks and act as gateways, directing traffic between LANs and WANs. Switches handle data forwarding within a LAN, and three‑layer switches can perform limited routing functions. Access Points serve as wireless switches, allowing wireless devices to join the network.

Author: Yaaan_xu

Source: https://sspai.com/post/64074