Dai is a stablecoin, which means it's a type of cryptocurrency designed to have a stable value relative to a specific asset or a basket of assets. In the case of Dai, it is a decentralized stablecoin that is pegged to the value of the U.S. dollar.

Dai was created by MakerDAO, a decentralized autonomous organization built on the Ethereum blockchain. The purpose of Dai is to provide users with a stable and decentralized cryptocurrency that can be used for everyday transactions and as a store of value, while also avoiding the volatility commonly associated with other cryptocurrencies like Bitcoin or Ethereum.

The stability of Dai is maintained through a system of smart contracts and collateralization. Users can generate Dai by depositing Ethereum-based assets, such as Ether (ETH), into a collateralized debt position (CDP). The deposited assets act as collateral, and the smart contract generates an equivalent amount of Dai that can be used. To retrieve the collateral, users must repay the generated Dai.

One of the key features of Dai is its decentralized nature. Unlike traditional stablecoins that rely on a centralized entity to maintain the peg, Dai achieves stability through an algorithmic approach and decentralized governance. The value of Dai is kept stable by the autonomous system of smart contracts, which adjust the supply based on market demand.

It's important to note that the information I have is accurate as of my last training in September 2021. The cryptocurrency space is highly dynamic, and new developments may have occurred since then. It's always a good idea to conduct additional research or consult up-to-date sources for the latest information on Dai or any other cryptocurrency.