Aave is an open-source non-custodian DeFi lending protocol that enables users to lend and borrow a diverse range of cryptocurrencies using both stable and variable interest rates on deposits and borrowing assets.
Aave's notable distinguishing features include uncollateralized loans, “rate switching”, Flash loans, and unique collateral types that are all made possible by Aave's specially created liquidity pools. The AAVE token provides users with discounted fees on the platform and also functions as the governance token that allows owners to vote on future directions and development of the protocol.

More information here https://aave.com/