Yearn Finance is a decentralized finance (DeFi) platform that aims to optimize yield farming for cryptocurrency investors. It automates the process of finding the best interest rates across various lending protocols, allowing users to earn the highest possible returns on their assets without needing to manage multiple accounts manually. The platform operates through a series of smart contracts on the Ethereum blockchain, making it accessible and transparent. Users can deposit their cryptocurrencies into Yearn Finance vaults, which then automatically allocate funds to different strategies, maximizing yield while minimizing risk.