Duke University finance professor Campbell Harvey and practitioners Ashwin Ramachandran and Joey Santoro wrote this rigorous academic-practitioner hybrid at the height of the DeFi explosion in 2021, providing what remains the clearest and most analytically serious overview of decentralized finance and its implications for the global financial system. The book begins with a systematic critique of the five fundamental flaws in the traditional financial system — centralized control, limited access, inefficiency, lack of interoperability, and opacity — and demonstrates how DeFi protocols address each through smart contracts, permissionless access, automated market makers, composability, and on-chain transparency. Coverage includes the mechanics and economics of decentralized exchanges using automated market maker models, lending and borrowing protocols including over-collateralized lending and flash loans, stablecoins and their different risk profiles (algorithmic, crypto-collateralized, and fiat-backed), yield aggregators, and synthetic asset protocols. The authors are unusually rigorous on the risks of DeFi — smart contract vulnerabilities, oracle manipulation attacks, governance centralization, and systemic leverage — maintaining the intellectual honesty that distinguishes this from more promotional treatments of the space. The concluding sections on the regulatory landscape and the potential for DeFi to improve financial access in developing economies provide essential context for understanding DeFi's long-term trajectory. One of the essential reference texts for any serious student of decentralized finance.