What is a network?

The smallest network there is

Take two computers and plug one cable between them. Congratulations: you've built a network. That's really all the word means. A network is a group of devices that are linked together so they can send information back and forth and share things.

The devices on a network are often called nodes or hosts. They don't have to be computers. Phones, printers, game consoles, smart TVs, security cameras and even thermostats all join networks today.

What do devices share?

Once devices are connected, they can share almost anything that can be turned into data:

• Files, like photos copied from your phone to your laptop
• Devices, like one printer used by the whole house
• An internet connection, so every device can get online through one box
• Live streams, like a movie playing from a streaming service or a game lobby with your friends

Networks come in sizes

Your home is a network. Your phone, laptop, TV and maybe your fridge all talk through the box on your shelf (episode 2 opens that box up).

A school or office is a bigger network, with hundreds or thousands of devices and a lot more cable running through the walls and ceilings. Networks that cover a single home, building or campus are called local area networks, or LANs.

Networks that stretch across cities or countries, connecting LANs that are far apart, are called wide area networks, or WANs.

The internet: a network of networks

Now take millions of home, school and office networks and connect them all together, across cities, oceans and continents, using cables, satellites and giant data centers. That's the internet.

The internet isn't one single machine or one company's network. It's thousands of separate networks, run by internet providers, businesses, universities and governments, that agree to pass each other's traffic along. When you load a website, your data might travel through several of those networks before it reaches you.

Try it yourself

Open your router's app or your Wi-Fi settings page and look for a list of connected devices. Count them. Most homes have far more devices on the network than people expect, and it's a fun way to spot the surprise ones (smart plugs, we're looking at you).

For CCNA learners

This lesson lines up with CCNA 200-301 exam topic 1.1, network components. You don't need to memorize anything yet. Just get comfortable with the idea that every network, no matter how big, is devices plus the links between them.