The Curve protocol allows exchanges between stablecoins, at the best possible rate and by limiting fees. It is therefore a decentralized exchange based on Ethereum, specializing in stablecoins. The principle of operation is based on liquidity pools, so instead of directly exchanging tokens between them, users will trade directly against a smart contract. This will recover the asset to be exchanged and return the one desired by the buyer at the current exchange rate.
Curve has a particularity, it allows extremely low slippage during trades. This is made possible by the function used by the protocol's automated market maker -AMM-.