Beanstalk is a permissionless fiat stablecoin protocol built on Ethereum.
Beanstalk forms the monetary basis of an Ethereum-native, rent-free economy facilitated by the seigniorage of its native fiat currency, a stablecoin called Bean.
A stablecoin that does not compromise on decentralization nor require collateral, has competitive carrying costs, and trends toward more stability and liquidity, will unlock the potential of DeFi. Beanstalk's primary objective is to incentivize independent market participants to regularly cross the price of 1 Bean over its dollar peg in a sustainable fashion.
You can find an overview of why Beanstalk was created here: