Computers and Devices
Why Keyboards Use the QWERTY Layout
QWERTY was born inside a nineteenth-century typewriter, and its odd letter order still shapes every phone and laptop today. Here is how it came about and why it stuck.
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Six categories to explore
Each category has 30 questions at three difficulty levels and its own set of articles.
Computers and Devices
From the keyboard layout you type on to the sensors that recognize your fingerprint, everyday devices are full of design decisions with a story behind them.
Internet and Connectivity
Airplane mode, Bluetooth, the cloud and encryption: what really happens when your devices talk to each other and to the network.
Everyday Inventions
Batteries, LEDs, solar panels, microwaves and induction cooktops: the physics behind gadgets we use without a second thought.
Image, Sound and Media
How QR codes and barcodes carry data, how cameras capture light, how compression shrinks files and how headphones erase noise.
Space and Communication
Radio waves, light in glass, cables on the seafloor and satellites overhead: how information and time travel across long distances.
Robotics and Machine Intelligence
How machines sense, decide and move: 3D printers, drones, robots, voice assistants and recommendation systems.
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Featured curiosity
The Sholes and Glidden typewriter went on sale in 1874 with a QWERTY-style keyboard, and that arrangement has outlived the machine it was designed for by well over a century.
Recommended articles
One deep dive from each category, a good place to start.
Internet and Connectivity
What Airplane Mode Really Does
Airplane mode is a single switch that shuts down a phone's transmitters. Here is which radios it silences, why cellular signals are the real concern, and what stays on.
Everyday Inventions
How Rechargeable Batteries Store Energy
A rechargeable battery does not hold electricity. It holds chemical potential, and lithium ions moving between two electrodes turn that potential into current and back again.
Image, Sound and Media
How a QR Code Stores Information
A QR code is a tiny map of black and white squares that carries text, a layout for finding itself, and enough redundancy to survive scratches and smudges.
Space and Communication
Why GPS Depends on Extremely Precise Clocks
GPS is really a timing system. A billionth of a second equals about 30 centimeters of error, which is why satellites carry atomic clocks and relativity must be corrected.
Robotics and Machine Intelligence
How Drones Stay Stable in Flight
A quadcopter is inherently unstable, yet it hovers almost motionless. The secret is a fast feedback loop that corrects errors hundreds of times per second.
Discover how it works
Three technologies in four steps
A quick look at ideas explained in depth in our articles.
Touchscreens
- A transparent grid of electrodes sits under the glass.
- Your finger, which conducts electricity, changes the electric field at that spot.
- The controller measures where the change is strongest.
- The device turns that position into a tap or a swipe.
QR codes
- A camera captures the square pattern of dark and light modules.
- Three large squares in the corners tell the reader orientation and size.
- The modules are read as bits and decoded into text or a link.
- Extra error-correction data can rebuild parts that are damaged.
GPS
- Satellites broadcast signals stamped with the exact time of sending.
- Your receiver measures how long each signal took to arrive.
- Distances to several satellites pinpoint your position.
- Tiny clock errors would become large position errors, so the clocks must be extremely precise.
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