The FREE online science and technology book
Want to know why giant ships can float, how your earbuds make music, what graphene is, or how windows can clean themselves? You've come to the right place! Here you'll find simple explanations you can really understand—hurrah!
Hard stuff... made simple!
Explain that Stuff is an online book written by science writer Chris Woodford (author of many popular science books for adults and children). It includes over 400 easy-to-understand articles, richly illustrated with clear artworks and animations, covering how things work, cutting-edge science, cool gadgets, and computers. We take the "pain" from explain and the "tough" out of stuff! There's more information on this website than in your average expensive science book, it's continually updated, and it's completely free to use! Explain that Stuff also helps to support curriculum learning (conventional STEM education and home-schooling).
How to use this site
There are five simple ways to find what you want:
A-Z index: Browse articles by name,
from accelerometers to zeolites... via induction motors, LCDs, and regenerative brakes.
Timeline: Find inventions by date,
from the prehistoric birth of solar energy to the development of quantum computers.
Random: Discover something new. Keep hitting "random" till you find something you like.
Search: Use our safe, Google-powered search engine.
Teaching guide: Browse a typical school curriculum to match articles from this site to topics you want to study or teach.
What's hot in January 2022?
In the news now...
Mirrors
NASA's James Webb Telescope has blasted into space carrying some of the most sophisticated mirrors ever developed. How do mirrors do their shiny stuff... and do they really flip things side to side as the science books tell us?
Solar power
Can the Sun save us? According to the US Energy Information Administration, solar made just 3 percent of US electricity in 2020, but that figure will reach 20 percent by 2050. Just in time... or too little too late?
Climate change
Last year was the sixth hottest on record, tied with 2018, but the hottest ever for almost a quarter of the world's people. If you find the whole subject of "global warming" baffling, try our ever-popular, simple introduction—completely updated for 2021.
Virtual reality
Facebook's having another go at moving us into its virtual dream-world; it's latest effort is called the "metaverse." But what is virtual reality... and where did the idea come from?
What's new for '22?
We have a few brand new articles on the site... and more to come in the next few months:
Artificial intelligence
Can we imagine a world where computers are smart enough not to need us?
Gravity
It's taken over two millenia for people to understand how gravity holds the universe together. What do we know so far about this most mysterious of forces?
History of flight
How did humans soar to the sky... and why did it take us so long?
Cranes
The science behind cranes is easy to understand, but why are there so many different types? How much can they lift... and what stops them toppling over?
History of electricity
Why did it take so long for people to harness electricity? We explore the sparky story of electric power.
Software
Computers are wonderful machines you can reprogram to do almost anything. How does "software" make that work?
Great psychology experiments
People are never quite what we seem—as these 10 fascinating experiments from psychological science clearly demonstrate!
What is science—and why does it matter?
Why is science still our best hope for making sense of the world?
History of communication
How did we get from the alphabet to the Internet in about three to four thousand years?
Most popular
These are some more of our classic, ever-popular articles:
- Water pollution: Rivers and seas take a long time to recover from the effects of careless human treatment. What causes pollution and what can we do to stop it?
- Electricity: The most versatile and useful form of energy in our world, electricity is going to become a whole lot more important in future.
- Nanotechnology: Can we build a brave new world just by shuffling atoms and molecules under a microscope?
- Magnetism: One of the first bits of science people studied, magnetism is still just as relevant today in everything from electric cars to body scans at the hospital.
- Gears: Wheels with teeth carved around them can make you go faster or bump up your power—and here's how.
- Batteries: We all need electricity, wherever we happen to be, so thank goodness for batteries—miniature power plants you can carry in your pocket.
- Electric motors: These amazing machines turn electricity and magnetism into movement, powering everything from handheld toothbrushes to bikes, cars, and trains.
- Cloud computing: Why buy yourself an expensive computer or programs to go with it when you can get access to something just as good over the Internet?
- Global warming: Is the planet really heating up? What can we do about it?
What else is on our site?
The articles on our site are divided up into broad topical areas, listed below. We've also given you a rough idea of the kind of questions you're going to find answers to in each section:
- Communications: Why do we bounce telephone calls off satellites? How do cellphones work? What's the difference between digital radio and ordinary radio?
- Computers: How can you make a computer think like a human brain? Who invented the computer—and why on Earth did it take them so long?
- Electricity and electronics: How can you make coffee with a stream of electrons? How can magnets detect burglars in your home?
- Energy: How does wind energy come from the Sun? Is nuclear power safe or not?
- Engineering: What stops a bridge falling over? How come a person can lift more stuff with a crane than with their bare hands?
- Environment: Can we still stop dangerous climate change? What causes air and water pollution and how can the world clean up its act?
- Gadgets: How does a flash memory card store your holiday snaps? Why can a synthesizer mimic any musical instrument that's ever been invented (and even ones that haven't been)?
- Home life: How can you make windows turn dark at the flick of a switch? How does an artificial leg work? If an energy-saving lamp saves energy, how come it still makes exactly the same amount of light?
- Materials: If you had a piece of platinum as big as a man, how much would it be worth? Why doesn't a dry-stone wall fall over? Is it true that glass is a kind of liquid?
- Science: Which part of a candle flame is the hottest? Why does chocolate actually taste good? Where's the best place to sit on a rollercoaster if you want to scare yourself to death?
- Tools, instruments, and measurement: How does an iris scanner recognize your eyes? Why don't fireproof clothes catch fire? Can a robot really learn to play drums?
- Transportation: If a man can't fly, how can a plane fly if it weighs as much as 5000 men? How come we say a wheel reduces friction if it's got a tire that grips the road?
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