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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).

How to use this site

There are five simple ways to find what you want:

Icon for browsing A-Z.  A-Z index: Browse articles by name, from accelerometers to zeolites... via induction motors, LCDs, and regenerative brakes.

Icon for browsing by date  Timeline: Find inventions by date, from the prehistoric birth of solar energy to the development of quantum computers.

Icon for random article  Random: Discover something new. Keep hitting "random" till you find something you like.

Icon for search engine  Search: Use our safe, Google-powered search engine.

Icon for loving STEM  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 September 2021?

In the news now...

Conceptual artwork of quantum computing.

Air pollution

A new study has found air pollution is shortening billions of people's lives by up to six years. Why, in the 21st century, is dirty air still such a big problem?


Conceptual artwork of quantum computing.

Climate change

According to the world's top scientists, climate change is now "widespread, rapid, and intensifying." If you find the whole subject baffling, try our ever-popular introduction—completely updated for 2021.


Recycling symbol

Recycling

In the United States, Maine and Oregon are planning to charge the cost of recycling to manufacturers instead of consumers. Why don't we recycle everything—and why are some materials recycled more easily than others?


Simplified illustration of space rocket parts

Space rockets

Sir Richard Branson has beaten Amazon's Jeff Bezos in the race to be the first rocket-powered billionaire in space. But what is "space" anyway... and what's involved in getting up there?


Conceptual illustration of hybrid car

Electric cars

President Joe Biden is pushing ahead with pollution-busting incentives to help switch the world to electric vehicles. What's so good about electric cars... and what are the drawbacks?


Conceptual illustration of atomic nucleus drawn together and pulled apart by forces

Nuclear fusion

There's more excitement over nuclear fusion after a recent experimental breakthrough at Britain's Culham research lab. What is nuclear fusion and could it really solve our energy-environment crisis?


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 suddenly talking about them?


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?

Optical mouse circuit board with red LED light shining through light guide.

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:

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Our website serves advertisements to pay its running costs. The advertisers we work with use a technical mechanism called cookies (small files stored on your computer) to help them serve relevant and useful advertisements that they think are likely to appeal to you, but you can opt in or out of these cookies at any time. The web domain explainthatstuff.com does not collect, store, sell, or share any personal information and has no plans ever to do so in the future. However, in line with the California Consumer Privacy Act (CCPA), you may still send us a "Do Not Sell My Personal Information" request if you'd like to. For more details, please see our privacy policy.

Please do NOT copy our articles onto blogs and other websites

Articles from this website are registered at the US Copyright Office. Copying or otherwise using registered works without permission, removing this or other copyright notices, and/or infringing related rights could make you liable to severe civil or criminal penalties.

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

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