DeFi stands for decentralized finance, but it's really more like open finance. Until now, the history of finance has been centralized or closed. You go up to a bank or some other kind of financial service provider and you engage in a relationship with them where they promise they'll do certain things... But, ultimately, you're putting your money into a black box and you're hoping—and trusting—that they're going to do it exactly like they said. Decentralized finance (DeFi) is an effort to deconstruct that and make all those pieces open and transparent.