What Is the Internet? How a Message Crosses the World in One Second
The internet is not a cloud floating in the sky. It is millions of computers joined by real cables, most of them lying on the bottom of the ocean.
The whole idea, in one diagram
Your device asks a question: please send me this page.
The question travels through your router and along cables to a computer called a server.
The server sends the answer back, cut into thousands of tiny pieces that are put together at your end.
What problem did it solve?
Every computer was an island. To move work from one machine to another you carried a tape or a box of punched cards across the room, or posted it and waited days. Two computers made by different companies usually could not talk at all.
Engineers agreed on a shared set of rules, so that any computer anywhere could pass a message to any other, even if the two machines had nothing else in common.
Distance almost stopped mattering. A doctor in Karachi can read a scan from London, a class can watch a lesson made in another country, and a message reaches the far side of the planet before you can put your phone down.
How it started
- 1969
The first message on ARPANET
👤 Charley Kline, a student at UCLA, sending to Stanford
On 29 October 1969 the team tried to send the word LOGIN between two computers 560 kilometres apart. The system crashed after two letters, so the first message ever sent was LO.
Why it mattered: It was the first time two distant computers held a conversation. Everything else on this page grew out of that one broken word.
- 1971
The first email, and the @ sign
👤 Ray Tomlinson, USA
Tomlinson sent a message between two computers and chose the @ symbol to separate the person from the machine they were on.
Why it mattered: Email became the first thing ordinary people wanted a network for. The @ in every address today is his choice.
- 1974 to 1983
TCP/IP, the shared rulebook
👤 Vint Cerf and Bob Kahn, USA
They designed a set of rules for cutting a message into small packets, addressing each one, and rebuilding them in the right order at the other end. On 1 January 1983 the whole network switched over to it.
Why it mattered: This is the moment separate networks became ONE internet. Any machine that follows the rulebook can join, which is why it never had to be rebuilt.
- 1983
Names instead of numbers
👤 Paul Mockapetris, USA
Every computer on the internet has a number, like 142.250.1.100. Mockapetris invented the Domain Name System, a giant phone book that turns a name people can remember into that number.
Why it mattered: Without it you would have to memorise a string of digits for every website. DNS is why you can type a name and simply arrive.
- 1989 to 1991
The World Wide Web is invented
👤 Tim Berners-Lee, at CERN in Switzerland
He proposed a way to write pages, link them to each other and fetch them over the internet. The first website went live in 1991, and he gave the whole idea away for free.
Why it mattered: The internet is the roads. The web is the traffic that made everybody want to use them. Because he refused to charge for it, anyone could build on top.
- 1998
Finding things in the mess
👤 Search engine builders, including Google
As pages multiplied into millions, nobody could find anything. Search engines began reading the whole web and ranking pages by how useful they seemed.
Why it mattered: A library is useless without a catalogue. Search is what turned a pile of pages into something you could actually use.
- 2007 onwards
The internet goes in your pocket
👤 Smartphone makers, and mobile networks worldwide
Phones with real browsers and fast mobile data meant the internet was no longer something you sat down at.
Why it mattered: For most people on Earth today, a phone is their only way onto the internet. They never used a desktop at all.
Who made it happen
Vint Cerf and Bob Kahn
1974 · USA
Wrote the shared rules, TCP/IP, that let any computer talk to any other. They are often called the fathers of the internet.
Tim Berners-Lee
born 1955 · England, working at CERN
Invented the World Wide Web in 1989 and gave it away free, so anybody could use it without permission or payment.
Paul Mockapetris
1983 · USA
Invented the Domain Name System, the phone book that turns a website name into the number a computer needs.
Ray Tomlinson
1941 to 2016 · USA
Sent the first network email and picked the @ sign, which is now in every email address in the world.
Radia Perlman
born 1951 · USA
Invented a method that stops network messages going round in circles forever. It quietly keeps large networks working.
Charley Kline
1969 · UCLA, USA
A student who typed the very first message sent between two distant computers. It crashed after two letters.
What happens in the second after you tap a link
- 1
Your device looks up the name
You type a name like learningappforkids.com. Your device asks the Domain Name System for the number that belongs to that name, because computers find each other by number, not by name.
- 2
It sends a request
Your device writes a short message that means please send me this page, and hands it to your router, the box that connects your home to the outside world.
- 3
The request hops across the world
The message passes from machine to machine, each one looking at the address and passing it towards the destination. It may cross ten or twenty of these hops, often through cables lying on the seabed.
- 4
A server answers
A server is just a computer whose job is to wait and answer. It finds the page you asked for and sends it back, chopped into thousands of small packets.
- 5
Your device rebuilds the page
The packets can arrive out of order or go missing. Each one is numbered, so your device puts them back in order and asks again for any that never turned up.
- 6
The browser draws it
Finally your browser reads the files and paints the page: the words, the pictures, the colours and the buttons. All of that usually happens in well under a second.
Each invention solved the last one's problem
Letters and telegrams
- Problem before
- A message moved at the speed of a horse, a ship or a train. Asking a question and getting an answer could take weeks.
- What it solved
- The telegraph put messages onto wires, so words could cross a country in minutes instead of days.
- Impact
- News, trade and railways sped up, but you still needed an operator at each end and could only send short text.
Telephone lines
- Problem before
- Telegrams were short, expensive and needed a trained person to tap them out.
- What it solved
- Phone lines carried a live human voice between two houses.
- Impact
- Ordinary people could talk across distance. But a line joined only two people at a time, and computers could not use it well.
The internet
- Problem before
- Computers could not share anything, and every network was a separate island with its own rules.
- What it solved
- One shared rulebook, TCP/IP, let any machine send anything to any other machine, in small numbered packets.
- Impact
- Text, pictures, sound, video, money and lessons all travel on the same network. Distance stopped being the main cost.
Mobile internet
- Problem before
- You had to be sitting at a desk, in a building, plugged into a wall.
- What it solved
- Radio masts and pocket computers put the whole network in your hand, wherever you stood.
- Impact
- Billions of people came online who had never owned a computer. For most of them the phone IS the internet.
Watch it happen, step by step
Tap through the animation. You can switch it to Urdu with the button.
When you tap a video — how does it get to you?
The internet is not stored anywhere. It is an agreement: millions of separate computers all following the same rules for passing messages along.
Ask a grown-up to help you look up a map of undersea internet cables online. Find the cables that reach your own country, then trace where they come ashore. Almost everything you watch or send travels through one of those lines on the seabed.
Key words on this page
- The Internetانٹرنیٹ
- The internet is millions of computers all over the world connected together so they can talk to each other. It is like a giant invisible road system, but for information instead of cars. When you use it, your computer joins all those other computers!
- Did you know? Right now, more than 5 billion people around the world use the internet!
- A Websiteویب سائٹ
- A website is like a page, or lots of pages, that someone has put on the internet for everyone to read and explore. Just like a book has pages full of words and pictures, a website has pages full of information. YouTube, Google, and your school's site are all websites!
- Did you know? There are over 1 billion websites on the internet today!
- A Browserبراؤزر
- A browser is a special app that lets you look at websites, it is your window to the whole web! Chrome, Safari, and Firefox are all browsers. You type an address into the browser and it fetches that website for you to see.
- Did you know? Google Chrome is the most popular browser in the world, used by more than half of all internet users!
- A Linkلنک
- A link is like a magic door! When you tap or click it, it takes you straight to another page or website. Links are usually underlined or a different colour so you know where to tap. They are how we jump around the whole web!
- Did you know? Tim Berners-Lee invented links so that one page could point to any other page anywhere in the world!
- Wi-Fiوائی فائی
- Wi-Fi sends the internet through the air using invisible radio waves, just like how a radio plays music without wires! A little box called a router at home or school sends these waves out. Your tablet or phone catches the waves and gets connected.
- Did you know? Wi-Fi signals can pass through walls, that is why you can use the internet in any room of your house!
- Internet vs World Wide Webانٹرنیٹ بمقابلہ ورلڈ وائڈ ویب
- No, they are different! The internet is like the roads and motorways connecting every city. The World Wide Web is like all the shops, houses, and buildings that sit along those roads. You need the internet (roads) to reach the Web (buildings), but they are not the same thing.
- Did you know? Tim Berners-Lee invented the World Wide Web in 1989, but he gave it to the whole world for free!
- Packets — How Messages Travelپیکٹس — پیغام کیسے سفر کرتے ہیں
- When you send a message or video, it gets chopped into thousands of tiny pieces called packets, a bit like cutting a big letter into many postcards. Each packet finds its own fastest route to reach the other computer, then they are all put back together perfectly at the other end.
- Did you know? A single YouTube video is broken into thousands of packets that may travel different routes before joining back together on your screen!
- Search Enginesسرچ انجن
- A search engine like Google constantly visits billions of web pages and makes a huge list of what they are about. When you type a question, it looks through that list super fast and shows you the most helpful pages. It is like a librarian who has read every single book in a giant library!
- Did you know? Google answers more than 8 billion searches every single day!
- Email and Video Callsای میل اور ویڈیو کالز
- Email is like a digital letter, you write it, hit send, and it arrives in seconds anywhere in the world. Video calls use a camera and microphone so you can see and hear each other live, even if one person is in Pakistan and the other is in another country!
- Did you know? Around 330 billion emails are sent every single day around the world!
- Staying Safe Onlineآن لائن محفوظ رہنا
- Always ask a grown-up before visiting a new website or talking to someone online. Never share your name, address, school, or photos with strangers on the internet. Be kind to others online, just like you would be in real life, and if something feels wrong, tell a trusted adult straight away!
- Did you know? A password is like a secret key, never share it with anyone except your parents!
- Servers and How Websites Loadسرور اور ویب سائٹ کیسے کھلتی ہے
- A server is a powerful computer that stays switched on all the time and stores websites. When you type a web address, your browser sends a request to that server, and the server sends the page back to you across the internet in a fraction of a second. It all happens so fast it feels instant!
- Did you know? There are more than 10 million servers working around the world right now to serve websites to people!
- IP Addresses and URLsآئی پی ایڈریس اور یو آر ایل
- Every device on the internet has a number called an IP address, like a house number for your computer. A URL (web address like www.google.com) is the friendly name for that number, the way a house has both a number and a name. When you type a URL, the internet looks up the matching number to find the right server.
- Did you know? Your IP address can roughly show which city you are in, that is why some websites can greet you in your own language automatically!
- The Cloudکلاؤڈ
- The cloud is not really a cloud in the sky, it means saving your photos, videos, and files on powerful servers connected to the internet. Instead of only being on your phone, they are kept safe in a big building full of servers somewhere else. That is why you can see your photos on any device, even if your phone breaks!
- Did you know? Companies like Google and Amazon have buildings the size of several football fields full of servers, that is the cloud!
- Cryptocurrency and Blockchainکرپٹو کرنسی اور بلاک چین
- Cryptocurrency is money that exists only on the internet, there are no coins or notes, just numbers stored on computers. To make sure nobody cheats, every transaction is recorded in a special shared list called a blockchain. Thousands of computers all hold a copy of this list, so no single person can secretly change it.
- Did you know? Bitcoin was the world's first cryptocurrency, created in 2009, and nobody knows for sure who invented it!
- How the Whole World Connectsپوری دنیا کیسے جڑی ہے
- Underneath the oceans there are thousands of kilometres of special cables carrying internet data between continents at the speed of light. Satellites in space also beam internet signals down to places where cables cannot easily reach. These undersea cables and satellites are what make the whole world one connected network!
- Did you know? There are over 400 undersea internet cables stretching more than 1.3 million kilometres across the ocean floors, enough to wrap around the Earth 32 times!
Quiz: how much did you remember?
Quiz time!
10 questions, picked at random from 30. No sign-in and no score is kept. Play as many times as you like, the questions change every time.
Questions about the internet
What is the internet in simple words?
The internet is a huge number of computers all over the world, joined together by cables and radio, that agree to follow the same rules for passing messages. Anything you send is cut into small pieces, addressed, and reassembled at the other end.
What is the difference between the internet and the World Wide Web?
The internet is the roads. The web is one kind of traffic on those roads: the pages you look at in a browser. Email, video calls and games also use the internet but are not part of the web.
Who invented the internet?
No single person. The first network, ARPANET, sent its first message in 1969. Vint Cerf and Bob Kahn wrote the shared rules in the 1970s. Tim Berners-Lee invented the World Wide Web on top of it in 1989.
Is the internet really in the cloud?
No. The cloud is just somebody else's computer, sitting in a big building called a data centre. Your photos are on a real machine in a real room, and they got there along real cables.
How does the internet cross the ocean?
Through cables lying on the seabed, some of them thinner than a garden hose and thousands of kilometres long. Almost all international internet traffic goes through these cables, not through satellites.
What is a server?
A server is an ordinary computer with a special job: it waits for requests and answers them. When you open a website, a server somewhere finds the page and sends it to you.
What is Wi-Fi? Is it the same as the internet?
No. Wi-Fi is just the last few metres, the radio link between your device and your router. The internet is everything beyond the router. You can be connected to Wi-Fi and still have no internet at all.
Why is my internet sometimes slow?
Usually because the road is busy. Many devices may be sharing one connection, the server you are asking may be far away or overloaded, or your Wi-Fi signal may be weak because of distance or walls.
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