DeFi platforms are decentralized financial applications built on blockchain that allow users to access services like lending, borrowing, staking, and trading without intermediaries. They rely on smart contracts to automate transactions and ensure transparency and security. Popular DeFi platforms, such as Aave, Compound, and MakerDAO, enable individuals to earn interest, access liquidity, and manage their assets with greater control. By utilizing blockchain's decentralized nature, DeFi platforms offer financial services with lower fees, greater efficiency, and enhanced privacy.