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How the Internet Works: fun facts and quiz
The essentials in 7 ideas, with fun facts, an illustrated story and a quiz to see how much you know.
The essentials
What the Internet Is
The internet is a global network of networks: billions of devices linked by cables, radio and satellites, all following shared rules called protocols.
Key fact
About 99% of international data travels through undersea cables.
Packets
Data travels in small packets. Each finds its own route across the network and they’re put back together at the end, so one broken link doesn’t stop the message.
Key fact
A single web page can arrive as hundreds of packets.
IP Addresses
Every device online has an IP address, a number that tells packets where to go, like a postal address.
Key fact
The older IPv4 system has only about 4.3 billion addresses.
DNS
DNS is the internet’s phone book. It turns names like example.com into the IP addresses computers actually use.
Key fact
Your devices make DNS lookups many times a day.
Where It Began
The internet grew from ARPANET, a US research network that sent its first message in 1969. The shared TCP/IP rules were switched on in 1983.
Key fact
The first message was meant to be “LOGIN”; it crashed after “LO”.
Wi-Fi & Mobile Data
Wi-Fi links devices to a router by radio over short distances. Mobile networks like 4G and 5G use cell towers to cover whole regions.
Key fact
Wi-Fi mostly uses the 2.4 and 5 GHz radio bands.
Speed & Latency
Bandwidth is how much data flows per second; latency is how long a packet takes to arrive. Online gamers care most about low latency.
Key fact
Data in fibre travels at about two-thirds the speed of light.
Fun facts
The word “internet” is short for “internetworking”: connecting separate networks together.
Packet switching was invented twice, independently, in the 1960s: by Paul Baran in the US and Donald Davies in the UK.
The address 127.0.0.1 always means “this computer”, hence the geek joke “There’s no place like 127.0.0.1”.
Before DNS, the names and addresses of every computer online were kept in one shared file, updated by hand.
Ray Tomlinson sent the first email using the @ sign in 1971.
Wi-Fi owes part of its origins to Australian radio astronomers who were searching for signals from exploding black holes.
Traders once paid for a new, straighter cable between Chicago and New York just to shave milliseconds off their trades.
Story: Lo and Behold
Lo and Behold
29 October 1969, late evening. At UCLA, student Charley Kline starts typing “LOGIN” to a computer about 500 km away, at Stanford Research Institute.
A colleague there checks each letter by phone. “Did you get the L?” Yes. “The O?” Yes. On the G, the system crashes.
So the first message on the network that grew into the internet was “LO”, as in “lo and behold”. An hour later, the full login worked.
True or false?
Tap your answer to see if you got it, and why.
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Question 1 of 10
Most international internet traffic travels through undersea cables.
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True. Not satellites, as many people assume.
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Question 2 of 10
Packets from one message can take different routes.
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True. They’re reassembled at the destination.
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Question 3 of 10
An IP address helps data find the right device.
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True. Like an address on an envelope.
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Question 4 of 10
DNS turns website names into IP addresses.
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True. Computers need the numbers, people prefer names.
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Question 5 of 10
The internet grew out of ARPANET.
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True. A US research network from 1969.
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Question 6 of 10
Wi-Fi uses radio waves.
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True. Short-range radio between your device and a router.
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Question 7 of 10
Latency is the delay before data arrives.
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True. Often measured in milliseconds, as “ping”.
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Question 8 of 10
The internet and the web are exactly the same thing.
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False. The web is one service that runs on the internet, like email.
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Question 9 of 10
The internet reserves one fixed line for each whole message.
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False. That’s how old phone lines worked. The internet uses packets.
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Question 10 of 10
IPv4 has enough addresses for every device there will ever be.
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False. It ran short, so the much bigger IPv6 was created.
Keep going in the app
KnowSoda learns what you know and brings back what you’re about to forget. How the Internet Works has 6 more ideas at the Advanced and Expert levels.
