You are here: Home page

The FREE online science and technology book

CCD chip from a webcam.

Atoms Under the Floorboards book cover

  • WhatsApp share
  • Tweet

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, including Atoms Under the Floorboards: The Surprising Science Hidden in Your Home). 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 January 2021?

In the news now...

Simulated image showing light emerging from a fiber-optic cable

Fiber optics

Narinder Kapany, the Indian-born pioneer of fiber optics, has just died at the age of 94. We learn in school that light travels in straight lines, but Kapany's genius insight was to realize there are ways of making it "bend" down cables.

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

Space rockets

China's Chang'e 5 probe has brought back the first new samples from the Moon for decades. But how exactly do you put a rocket into space?

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 end an estimated 7–10 million lives a year?

Diagram showing the sequence of power-making steps inside a nuclear electricity power plant.

Nuclear power

NASA is considering using nuclear fission (splitting atoms) to power future space rockets to Mars. Why do you get so much energy when you split an atom?

Simple diagram showing the difference between serial and parallel processing in computer systems.


Plans to launch the world's first "exascale" supercomputer in the USA in 2021 have suffered a major setback. Meanwhile, Fugaku, at RIKEN Center for Computational Science (R-CCS) in Japan remains the fastest machine on Earth.

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:

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.

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