LANs and WANs

Think about the computers in your school. The machines in the ICT room, the laptops on the trolley, the printer in the library and the teacher's PC can all talk to each other, share files and use the same printer. Now think about watching a video from a company on the other side of the world — that data crosses cables under the sea to reach you. Both of those are networks, but they are very different sizes. To tell them apart, we split networks into two big families: the LAN and the WAN.

This page is all about one clear idea: what makes a network a LAN or a WAN comes down to how far it spreads and who owns the connections — not how many computers are plugged into it.

The LAN — a Local Area Network

A LAN (Local Area Network) joins computers and devices together across a small, local area on a single site — a home, a school, or one office building. Because everything sits close together (usually within a few hundred metres), the organisation can lay its own cables and buy its own equipment.

Three things are usually true of a LAN:

Small area — one building or a group of buildings on the same site.
Owned by the organisation — the school or company owns the cables, switches and routers, so it does not pay a phone company to rent them.
Fast — short, dedicated cables (or a private Wi-Fi network) mean data travels quickly, often at gigabit speeds.

The WAN — a Wide Area Network

A WAN (Wide Area Network) connects LANs together across a large geographic area — between towns, cities, or even countries. A supermarket chain, for example, has a LAN in every shop, and a WAN joins all those shops to the head office so tills, stock and email work everywhere.

Compare it with the LAN:

Large area — spans long distances, sometimes worldwide.
Connections often not owned by the organisation — you cannot dig up hundreds of miles of road, so companies lease lines from a telecommunications provider (a phone/internet company) instead.
Usually slower than a LAN, because the data travels much further over shared, rented infrastructure.

The biggest WAN of all is the one you use every day: the internet is a gigantic WAN linking billions of networks across the planet.

See the difference

On the left is a LAN: several devices inside one building, wired to the organisation's own equipment. On the right is a WAN: separate sites (each with its own LAN) in different cities, joined by leased long-distance links. Step through the diagram.

LAN vs WAN at a glance

The three features that really matter — size, ownership and speed:

Feature	LAN	WAN
Area covered	Small — one site (home, school, office)	Large — towns, cities, countries
Who owns the links?	The organisation owns its own cables and hardware	Links are often leased from a telecoms provider
Typical speed	Faster (short, dedicated connections)	Usually slower (long, shared connections)
Example	Your school network	The internet

The hardware that makes it work

You do not need to know these in depth yet, but it helps to recognise the common pieces of network hardware that appear in a LAN and connect it to a WAN:

NIC (Network Interface Card) — the part inside a computer or phone that lets it join a network at all, by cable or Wi-Fi.
Switch — the box a LAN's wired devices plug into; it sends each message only to the device it is meant for.
Router — connects one network to another and finds a path between them. The router in your home links your LAN to the internet (a WAN).
WAP (Wireless Access Point) — lets devices join the LAN over Wi-Fi instead of a cable.

Inside one site it can, and does — that is exactly what makes a LAN a LAN. But laying cable across a whole country means digging up roads, crossing rivers, and getting permission for every metre in between. That is enormously expensive and slow, so organisations rent ready-made long-distance connections from telecoms companies who have already built that infrastructure. Not owning the links is a defining feature of a WAN — and the reason the internet could be built at all: everyone shares the same global network instead of each company building its own.

The difference between a LAN and a WAN is about geographic size and who owns the connections — not the number of computers. A small home network with three devices is still a LAN, and a huge school network with a thousand computers is still a LAN, because it all sits on one site and the school owns the cabling. Size of area and ownership decide it, never the head-count of machines.