Curve is an exchange liquidity pool on Ethereum (like Uniswap) designed for (1) extremely efficient stablecoin trading (2) low risk, supplemental fee income for liquidity providers, without an opportunity cost.
Curve allows users (and smart contracts like 1inch and Paraswap) to trade between DAI and USDC with a bespoke low slippage, low fee algorithm designed specifically for stablecoins and earn fees. Behind the scenes, the liquidity pool is also supplied to the Compound protocol or iearn.finance where it generates even more income for liquidity providers.
Curve smart contracts were Audited by Trail of Bits.
However, security audits don't eliminate risks completely. Please don’t supply your life savings, or assets you can’t afford to lose, to Curve, especially as a liquidity provider.
Using Curve as an exchange user should be significantly less risky, but this is not advice.
Before trading, you’ll have to approve Curve to interact with your stablecoin balance, similar to most DeFi applications.
On the exchange page, select the asset you would like to convert (e.g. USDC), and the quantity (e.g. 1,000) - the exchange rate, and quantity that you will receive (including and all slippage and fees) will be displayed. The exchange rate might surprise you - that’s the power of Curve.
Curve uses cTokens, or Ytokens assets for lending while market making, as the liquidity pool - this ensures that assets are always being put to work. You will need to acquire cTokens or YTokens if you want to provide liquidity (you can read the instuctions in each pool's FAQ).
This means using all USDC and DAI in your wallet. This way is recommended only if you have much less coins than currently in liquidity pool.
This means that you preapprove the contract to to be able to spend any amount of your coins when you interact with it. This means that you won't be asked every time to appove the amount of coins you want to transfer to the contract.
Go to the withdraw page. If you want to withdraw some percentage of your liquidity (the preferred way), type that percentage in the top field. You can, however, withdraw in a form of individual coins (USDC, DAI, ...), having the exchange happening for you, if you type amounts in lower fields. You'll get charge with the exchange fee in the latter case.