Decentralized finance (DeFi) is a broad term that describes the shift from traditional, centralized financial systems to peer-to-peer finance enabled by decentralized technologies built on the blockchain. Lending is one of the most promising areas for DeFi, with protocols like Aave, Maker DAO, and Compound Finance offering huge potential, while fintech companies like Hodlnaut, BlockFi, and Nexo offer lending services.