Page before the book starts : Introduction -- Shared space house : International Space Station -- Tiny bags of water you're made of : Animal cell -- Heavy metal power building : Nuclear reactor -- Red world space car : Curiosity Rover -- Bags of stuff inside you : Human torso -- Boxes that make clothes smell better : Washing machine and dryer -- Earth's surface : Physical map of the Earth -- Under a car's front cover : Car engine -- Sky boat with turning wings : Helicopter -- The US's laws of the land : US Constitution -- The US's Laws of the Land : USS Constitution -- Food-heating radio box : Microwave -- Shape checker -- Padlock -- Lifting room : elevator -- Boat that goes under the sea : Submarine -- Box that cleans food holders : Dishwasher -- Big flat rocks we live on : Tectonic plates -- Cloud maps : Weather maps -- Tree : Tree -- Machine for burning cities : Nuclear bomb -- Water room : Toilet and sink -- Computer building : Data center -- US Space Team's Up Goer Five : Saturn V rocket -- Sky boat pusher : Jet engine -- Stuff you touch to fly a sky boat : Cockpit -- Big tiny thing hitter : Large Hardon Collider -- Power boxes : Batteries -- Hole-making city boat : Oil rig -- Stuff in the Earth we can burn : Mines -- Tall roads : Bridges -- Bending computer : Laptop -- Worlds around the sun : Solar system -- Picture taker : Camera -- Writing sticks : Pen and pencil -- Hand computer : Smart phone -- Colors of light : Electromagnetic spectrum -- The sky at night : Night sky -- The pieces everything is made of : Periodic table -- Our star : Sun -- How to count things : Units of measurement -- Room for helping people : Hospital bed -- Playing fields : Athletic fields -- Earth's past : Geologic periods of Earth -- Tree of life : Life's family tree -- The ten hundred words people use the most : The ten hundred most common words in our language -- Helpers : Acknowledgments -- Sky toucher : Skyscraper.

The creator of the popular webcomic xkcd.com, a webcomic of romance, sarcasm, math, and language, uses line drawings and common words to provide simple explanations for how things work, including microwaves, bridges, tectonic plates, the solar system, the periodic table, helicopters, and other essential concepts. He uses line drawings and only the thousand most common words to provide simple explanations for some of the most interesting stuff there is. How do these things work? Where do they come from? What would life be like without them? And what would happen if we opened them up, heated them up, cooled them down, pointed them in a different direction, or pressed this button?