Maker is the system responsible for making DAI stable through “collateralized debt position” (CDPs) smart contracts on the Ethereum. MKR is an ERC-20 token created in response to insufficient collateral to back for DAI CDPs.
DAI is created through loan contracts which use Ether as a collateral. MKR Holders are responsible for regulating the collateralized rate making DAI consistently worth $1 and are rewarded for doing it; CDPs include a fee which is paid using MKR that is always burned, evating MKR's value.
CDPs are automatically liquidated in case Ether drops to a price such that their collateral (ETH) drops below a given value that is not enough to finance the amount of DAI loaned. If the liquidated volume recovered isn't enough to cover for the corresponding DAI volume loaned, the Maker system automatically creates new MKR tokens which are sold in open markets ensuring a positive balance. This mechanism incentives MKR holders to make rational decisions when voting for collateralized rates.
MakerDAO, the group responsible for Maker, also run a decentralized exchange called OasisDEX.