Imagine you’re shopping for a used car. The seller beams at you and says it runs perfectly — but you have no way to know if the engine is about to seize. You can’t trust the smile; you’ve seen too many “lemons.” So you offer a price that’s a rough guess, somewhere between what a great car and a clunker are worth. At that price, the owners of genuine cream puffs won’t sell, leaving mostly lemons on the lot. The market falls apart not because anyone is dishonest, but because one side simply knows more than the other. This chapter shows why that happens, and how smart business designs — from education to insurance menus to airline tickets — can piece the market back together.