You are here: Home page

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:

  1. A-Z index: Browse our articles by name.
  2. Timeline: Browse articles according to the history of science and technology.
  3. Random: Discover something new and unexpected.
  4. Search: Use our Google-powered search engine.
  5. Teaching guide: Match our articles to a typical home-school curriculum.

What's hot in April 2021?

In the news now...

Key parts of a helictoper, labeled artwork


NASA's just flown 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 suddenly 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 want to set tough targets to cut emissions. What's causing the climate crisis... and what's the solution?

Smokestack black smoke air pollution

Air pollution

A landmark inquiry in the UK made history recently 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.

Follow us on your favorite sites!

Now you've found us, don't lose us. Why not join our friendly Facebook page, where we post cool science and technology news? You'll find our photos on Flickr and we're also on Pinterest.

Save or share this page

Press CTRL + D to bookmark this page for later or tell your friends about it with:

Privacy and cookies

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 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.

More to explore on our website...

Back to top