How should a democracy choose its representatives? How does Covid-19 spread? How do computers teach themselves chess, and why is chess easier for them than analyzing a sentence? What should your kids study in school if they really want to learn to think? All of these are questions about geometry. Seriously! Jordan Ellenberg reveals the mathematics behind some of the most important scientific, political and philosophical conundrums we face. The word 'geometry', from the Greek, means 'measuring the world'. If anything, geometry doesn't just measure the world, it explains it. Shape shows us how.