DAI is a Stablecoin released by MakerDAO, a project that fuels the recent meteoric rise in decentralized finance (DeFi) applications. Unlike Tether which claims that all USDT tokens are backed 1-to-1 with US Dollars held at traditional bank accounts, DAI is backed by collateralized Cryptocurrency debt and managed by smart contracts. DAI keeps its price stable by dynamically adjusting the supply of DAI when the price deviates from the peg. 

More information here https://makerdao.com/