The global computer network called the internet is part of our everyday lives at home and at school.It is made up of millions of computers all over the world that are digitally connected to each other by cable, fibre or wireless links. You can use the internet to browse websites, communicate with people, download pictures and videos, listen to music or do lots of other amazing things.But have you ever wondered how the internet works?
Find out how information is broken down and sent across the internet.
If every bird’s nest was a computer, then the internet would be like connecting every bird’s nest together so they could all talk to each other. In computing speak, that’s called a network. But it’s not enough just to connect the nests together. The birds have to agree how they’ll use the connections too. Including how a message will be addressed and how it will get passed on. On the internet, these rules are called protocols. But what if you want to send something that’s too big? You would need to break it up into small pieces to get it there. The internet works in exactly the same way, but these small pieces are called packets. Each packet includes instructions about how it fits together and details about where it came from and where it is going. Each computer on the internet has a unique numeric address called an IP address, and these can be looked up automatically using a Domain Name Server, which is like a giant address book. When we have an address, the packets get guided through the internet by routers, which pass them along like a baton in a relay race. When the delivery arrives, the instructions explain how to put all the packets back together. Perfect!
Making a request
So how does information move around the internet?
Let’s imagine you are visiting a webpage with an image on it. How does the image get to your computer?
Sending a request
The image is hosted on a web server. Your computer sends a request to the web server for the image.
The request is sent in a ‘packet’. A packet is like a virtual parcel which has lots of important information attached to it. The two most important bits of information are the IP address of the web server that the image is stored on and the IP address of your computer.
Special computers called routers, and devices called switches, direct the packet from your computer to the web server. The web server might be close by or on the other side of the world.
Around the world
The packet can be sent across the world through fibre optic cables under the sea or even by satellite.
Receiving information
Now that the packet has arrived the web server opens it and reads your computer’s request, in this case ‘please send me this image’.
Images are often quite large so they need to be split up into lots of packets, often hundreds or thousands of them. All of these packets include information about how they should be put back together as well as where they are going and where they came from.
Different routes
The web server sends these packets back to your computer and once again routers and switches direct them.
The routers try to find the fastest possible route for each packet. They might take different routes and might not arrive in the same order they were sent.
Putting the packets back together
Now that all the packets have been received the information attached to them tells your computer how to put them back together and the image will display on your screen.
This whole process of sending a request and receiving the packets usually takes less than a second!
Glossary
Data packets
When information is being sent from one computer to another it is broken down into small bits of data called 'packets'. Each packet includes information about where the data is going to, where it is from and how to reassemble it.
IP address
Computers use an IP address (Internet Protocol address) to identify each other. It's a bit like a postcode that is unique to each computer connected to the internet. An IP address is a set of numbers that might look like this: 195.188.87.10.
Switch
A smart device that connects together many different devices so they can act as a network. Sometimes simpler devices called 'hubs' are used.
Router
A smart device that directs or routes information around the internet. When a data packet arrives the router reads the IP address information and sends the packet along the best route to its destination.
DNS
The DNS (Domain Name System) is a set of standards for how computers exchange data on the Internet. The DNS turns a user-friendly domain names like bbc.co.uk into an Internet Protocol (IP) address.
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