How does the internet work?
The internet is often thought of as a cloud – an abstract ‘place’ that websites float around in. In reality, the internet is a physical thing made of computers and wires – lots of wires.
The computers that make up the internet are known as servers. This is because they serve data to users – like a restaurant cooking up orders.
Any computer can be a server, but the term is normally used for computers specialised in shipping out data. To be completely accurate, a server is actually the program that handles this transfer of data.
We call computers servers when that is the only function they perform.
The servers of major companies and organisations are often located in data centres. These are buildings specifically to house servers and often contain several thousand of them.
These data centres are massive operations, typically using the same power consumption as a small town.
By keeping major servers within the same building, the speed of communication between these servers is greatly increased. If you are doing some online shopping and are then redirected to your bank, there’s a good chance that both the websites are contained in the same building.
The servers that make up the internet are connected by cables. Thousands of miles of undersea cable connect continents together, allowing for a worldwide network that computers can connect to.
More: What is an ISP?
To access the internet, you need to connect to it through one of these servers. This is where your ISP comes in.
If you didn’t have an ISP, you would have to physically connect to every server you wanted to access – meaning a lot of cables would need to be attached to your house. Instead, your ISP connects to these servers (with a lot of cables) and then sends the data to you.
What data is my ISP sending me?
When you visit a website, you are actually downloading a copy of the data on that website’s server to your own computer. This process involves sending a request to that server for data. If that request is fulfilled, the server sends that data to you. Once you have the data, you can see the website.
But the data isn’t sent to you in one piece. First, it is broken up into smaller chunks known as packets. Because a packet is a small piece of data, it can move faster and be processed more quickly than a complete file.
Imagine trying to carry a completed jigsaw puzzle through a busy city centre. You’d be walking very slowly, trying to avoid walking near anyone, desperately trying to keep your puzzle in one piece. If that puzzle was in pieces, it would be much easier to transport. This is why packets are created. Smaller pieces of traffic means faster connections for everyone.
Each packet is labelled with the address it is from and where it is going. These are known as IP addresses, and are sequences of numbers that computers use to recognise each other. Every device connected to the internet has an IP address. Without one, it would be impossible to receive any packets.
How does a packet find the address it’s heading to?
An IP address is a server’s place on the virtual map of the internet. However, it is also a place in the real world. The server exists somewhere, so how does a packet know which wires will lead to it?
The answer is: routers. These are similar to the router connecting your computer to the internet, but are often much larger and more powerful.
Guide: Is it worth buying a new router to get faster internet?
A router acts a junction – reading the IP address on a packet and sending it in the right direction. Packets will usually pass through several routers between a server and your computer.
What does my computer do with these packets?
Once your packets have reached you, the next step is rebuilding them into something useful. To do this, your computer uses protocols.
A protocol is a set of strict instructions that your computer follows to accomplish a task. If a file is broken into packets using a specific protocol, they can be rebuilt by using that same protocol. All your computer has to do is follow the instructions.
Because both computers are using the same instructions to construct packets, a file can be rebuilt identically to how it was sent – no matter how large or complex it might be. There are many different protocols involved in the internet, each one with a specific function, and a single packet will have several different protocols wrapped around it.
What if I don’t get all my packets?
Sometimes packets get lost and fail to reach their destination. This is normally caused by network congestion. If a router has to process more packets than it can handle, it has no choice but to ignore the extra packets entirely. Packet loss can also be caused by interference during their journey to a router.
Depending on the protocol being used, several different things can happen when you don’t receive all the packets you need. Your computer could wait while the packets are resent and then rebuild the file. Or, it could try and rebuild the file without the missing packets. If it doesn’t have enough packets to do this, or the packets take too long to be resent, it will be unable to complete the task.
This is why a bad connection results in slowdown, jitters, freezes or failure – they’re the different ways your computer reacts to receiving incomplete or slow packets.
A better connection means your computer can send and receive more packets at once. More packets means faster internet.
