When you deposit cryptocurrency with the popular DeFi protocol Compound, you are given a token that shows your investment. Yearn.finance lets you invest that token and get additional returns. Taking a crypto token, given as a proof of investment, and re-investing that proof elsewhere as an additional investment is a defining example of decentralized finance. YFI is at the forefront of DeFi culture and technology, trying to make it easier for non-technical crypto holders to maximize earnings.