What is a Network?

Think about your classroom at school. There are computers on the desks, maybe a big screen at the front, and one printer in the corner. Now here is the clever part: those computers are all joined together. Because they are joined, any computer can send its work to that one printer, open a file a friend saved, or share the school's internet.

When two or more computers are connected together so they can share things and talk to each other, that is called a network. That's the whole idea! A network is really just computers holding hands so they can help each other.

What does connecting let them share?

Once computers are on the same network, they can share all sorts of useful things:

Files — a photo, a story, or a picture you drew can be opened on another computer.
A printer — one printer can be used by every computer in the room.
The internet — one connection to the outside world can be shared by everyone.
Messages — computers can send each other messages, like passing a note.

Sharing is the reason networks were invented. Without a network, every computer would be a lonely island — you would need a printer for every single computer, and there would be no way to send a message across the room!

A picture of a little network

Here is a small network you might find in a home or a classroom. In the middle is a special box (grown-ups often call it a router or a hub) that all the devices connect to. Press play to watch each device join the network, one by one.

Once everything is linked to the middle box, a message can travel from any device to any other device. The laptop can print to the printer; the tablet can share a photo with the computer. They are all connected, so they can all share and talk.

Networks are all around you

You use networks every day, probably without even noticing:

The computers, printer and screen in your classroom are a network.
At home, the phones, tablets, laptops and TV joined to the same wifi are a network.
Even the whole internet is really a gigantic network — millions of computers all over the world, connected together.

Wires are one way to connect computers, but they don't always need wires. Wifi lets devices join a network using radio signals through the air — no cable needed. Wires or wifi, the big idea is exactly the same: computers connected so they can share and communicate.

As big as you like! A network can be just two computers connected in a bedroom, or it can be the entire internet with billions of devices spread across the whole planet. When you watch a video or send a message to a friend far away, your device is talking to another computer through this enormous worldwide network — all built from the same simple idea of connecting computers together.

Being connected is brilliant — it lets computers share and talk. But it also means you have to be a bit careful: once a computer is connected, other people and computers can reach it too, so we need rules to stay safe. (A later page is all about staying safe online.)

Also remember: a single computer on its own is not a network. You need at least two computers, and they have to be connected. One computer sitting alone has nobody to share with or talk to!