The FREE online science and technology book

Want to know how your earbuds make music, how telephones squeeze sounds down wires, why broadband is faster than dialup, or how science can make you happy? You've come to the right place!
Hard stuff... made simple!
Explain that Stuff is a collection of over 400 completely free,
easy-to-understand articles (and about 2000 photos and artworks), covering how
things work, cutting-edge science, cool gadgets, and computers.
Our mission is to explain things simply and clearly so you understand them completely.
There's more information on this website than in your average expensive science book—and it's all completely free to use!
(Our photos and artworks are also free for you to reuse in school reports, science fair projects,
and for other noncommercial uses under a
Creative Commons license.)
Most read
These are our top-ten most-read articles:
- Electricity: The most versatile and useful form of energy in our world, electricity is going to become a whole lot more important in future.
- 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?
- Global warming: Why is the world getting hotter and what can we do about it? What will be the consequences for humankind and the rest of the living world?
- Power plants: We wouldn't be able to do much without power plants buzzing away in the background making our electricity, but we've only had these remarkable energy factories for just over 100 years!
- Solar cells: Imagine being able to make electricity for free from nothing but sunlight! That's the promise of solar electricity, likely to be one of the most important forms of energy in the coming decades.
- Carbon monoxide detectors: Carbon monoxide is an odorless, invisible gas that can kill you very quickly; we investigate how electronic detector alarms can pick up a deadly gas your nose will miss...and save your life!
- Halogen cooktops: Can you boil an egg with nothing but light? Hi-tech halogen cooktops are convenient and easy-to-clean, but how exactly do they work?
- Air pollution: Doing a school or college project on pollution? Here's a comprehensive list of resources to help you get started.
- Wireless Internet: Who can still remember the time when everyone had to connect to the Net very slowly through a piece of copper wire? How exactly does Wi-Fi work?
- 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.
More popular articles...