AAVE Flash Loans

A flash loan is an unsecured, uncollateralized loan from a smart contract that must be borrowed and repaid in a single Ethereum transaction block. AAVE (Aave Protocol) is the largest flash loan provider, with $40B+ available to borrow. You call flashLoan(), specify amount and token, execute your logic, and repay principal + 0.05% fee, all in one atomic transaction. If you don't repay by end of block, the transaction reverts and never happened. This eliminates credit risk for lenders (they're only at risk if the protocol is hacked) and enables creative strategies for borrowers.