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The FREE online science and technology book

CCD chip from a webcam.

Breathless by Chris Woodford paperback book cover rendered as dummy 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).

What's hot in April 2021?

In the news now...

Key parts of a helictoper, labeled artwork

Helicopters

NASA's about to start flying a tiny helicopter on Mars. What's so good about rotating wings—and how do they really work?


Conceptual artwork of quantum computing.

Quantum computing

A British company claims it's found a way to build quantum computers from existing (silicon) computer chips. What exactly is a quantum computer... and why is everyone talking about them?


Artwork illustrating the greenhouse effect.

Climate change

Poorer nations want to keep burning fossil fuels to power their economic development, but richer nations are concerned about the impacts on the planet. What are the risks of a warming world?


Smokestack black smoke air pollution

Air pollution

A landmark inquiry in the UK has made history by ruling that air pollution killed a young girl living near a busy road. Why, indoors and out, does dirty air cause an estimated 7–10 million early deaths each year?


Artwork showing how a space rocket engine works by burning oxygen and fuel to make a hot exhaust gas.

Space rockets

The new Perseverance Rover has made a spectacular start to its mission exploring Mars, but it still takes a traditional rocket to put things like this into space. How exactly do rockets work?


Most popular

Model of a steam turbine at Think Tank science museum, Birmingham, England.

These are some more of our classic, ever-popular articles:

  1. 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?
  2. Electricity: The most versatile and useful form of energy in our world, electricity is going to become a whole lot more important in future.
  3. Nanotechnology: Can we build a brave new world just by shuffling atoms and molecules under a microscope?
  4. 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.
  5. Gears: Wheels with teeth carved around them can make you go faster or bump up your power—and here's how.
  6. Batteries: We all need electricity, wherever we happen to be, so thank goodness for batteries—miniature power plants you can carry in your pocket.
  7. Electric motors: These amazing machines turn electricity and magnetism into movement, powering everything from handheld toothbrushes to bikes, cars, and trains.
  8. 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?
  9. 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:

If you like this website...

... you might like my books. My latest one is Breathless: Why Air Pollution Matters and How it Affects You.

Covers of four recent books by Chris Woodford.

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Text on this website is copyright © Chris Woodford 2000, 2021. All rights reserved. Full copyright notice and terms of use.

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