In the traditional world, getting a loan takes weeks of paperwork and credit checks. In DeFi, you can take out a Flash Loan—a loan that is borrowed and repaid within a single blockchain transaction (which happens in seconds).
If the borrower doesn’t repay the loan in the same transaction, the entire thing “reverts” as if it never happened. This allows for Arbitrage: a trader can borrow millions in capital, buy a token on one exchange where the price is low, sell it on another where it’s high, and repay the loan—all in one go. While highly technical, it’s a prime example of how blockchain allows for financial maneuvers that were previously impossible for individual retail traders.