How Does the Internet Work for Kids?

You tap a link, and a second later a page from the other side of the world is on your screen. It feels instant, but a lot happens in that second. This guide follows the journey step by step.

What is the Internet?

The Internet is a huge network of computers that are connected so they can send information to each other. In fact, it is a network of networks. Your home has a small network. Your school has one. Companies, libraries, and phone providers have theirs. The Internet is what you get when all of those networks are linked together and agree to follow the same rules.

Nobody owns the whole Internet. Many different organizations own the pieces, and shared rules, called protocols, let those pieces work together.

The parts that get you online

Devices

Phones, tablets, laptops, game consoles, and smart TVs are all devices. Any device that can connect to a network can join the Internet.

Wi-Fi

Wi-Fi is a way to send information through the air using radio waves, so your device does not need a cable. Wi-Fi only covers a short distance, usually a home or a classroom. It connects your device to a nearby box called a router. Wi-Fi is not the Internet itself. It is just the last short hop between you and the router.

Routers

A router is a device that passes information from one network to another. The router in your home links your devices to each other and to the outside world. The Internet is full of much bigger routers that do the same job between cities and countries.

Internet service providers

Your home router connects to an Internet service provider, or ISP. This is the company your family pays for Internet access. The ISP runs the cables, or the mobile network, that link your home to the rest of the Internet. Many long-distance links are fiber-optic cables, including cables that lie on the ocean floor between continents.

How information travels: packets

Information does not travel across the Internet in one big piece. It is split into many small pieces called packets.

Think about mailing a jigsaw puzzle one piece at a time. Each envelope has the address it is going to, the address it came from, and a number showing where that piece fits. The envelopes might travel by different roads, and some might arrive out of order. When they all arrive, the numbers let you put the puzzle back together.

Packets work the same way:

• Each packet carries a small part of the information.
• Each packet is labeled with where it is going and where it came from.
• Routers along the way read the destination and pass the packet toward it, one step at a time.
• Packets from the same page can take different routes.
• When a reliable set of rules called TCP is used, missing packets can be noticed and sent again.

The labels on packets use IP addresses. An IP address is a number that identifies a device or a network on the Internet, a bit like a postal address identifies a building.

DNS: finding the right address

Computers find each other using IP addresses, but people are much better at remembering names. That is why websites have names such as example.com.

The Domain Name System, or DNS, connects the two. It works like the contacts list on a phone. You choose a name, and the phone looks up the number. When you type a website name, your device asks a DNS server, “What is the IP address for this name?” The server replies with the number, and your device can then send packets to the right place.

Websites, servers, and browser requests

A website is a collection of files, such as text, pictures, and videos. Those files are stored on a computer called a server. A server’s job is to wait for requests and send back what was asked for. Servers are often kept in large buildings called data centers.

The app you use to visit websites is a browser. Chrome, Safari, Firefox, and Edge are browsers. When you open a page, the browser sends a request to the server, and the server sends back a response. The rules for these messages are called HTTP.

When an address starts with https, the messages are scrambled while they travel so that others on the network cannot read them. This is called encryption.

Example: what happens when you open a website

Imagine a child named Sam types the name of a library website into a tablet and taps Go. Here is what happens next:

1. The browser needs an address. It asks a DNS server for the IP address that matches the website name.
2. DNS answers. The browser now knows which server to contact.
3. The request is sent. The browser writes a request for the page. The tablet splits it into packets and sends them by Wi-Fi to the home router.
4. The packets leave home. The router passes them to the ISP, and routers across the Internet forward them toward the server.
5. The server responds. It finds the page and sends it back, also split into packets.
6. The packets return. They travel back across the Internet to Sam’s router and then to the tablet.
7. The page is rebuilt. The tablet puts the packets in order, and the browser asks for anything else the page needs, such as pictures and fonts.
8. The page appears. The browser draws the finished page on the screen.

All of that usually takes less than a second.

Three common mix-ups

• “Wi-Fi is the Internet.” Wi-Fi is only the wireless link to your router. You can have strong Wi-Fi and no Internet if the router’s connection to the ISP is down.
• “The Internet is in the cloud.” “The cloud” means other people’s computers in data centers. Those are real machines that need buildings, electricity, and cooling.
• “Information travels through the air.” Only the first and last short hops are usually wireless. Most of the journey is through cables.

Questions to talk about

Parents and teachers can use these to check understanding:

• Where is the router in your home or classroom, and what does it connect to?
• Why might a video pause and load when many people are using the same connection?
• Why is it useful for information to be split into packets instead of sent as one big piece?
• What does DNS do, in your own words?