What Are Flash Loans? A Beginner's Guide to DeFi's Most Powerful Feature (Part 4)

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Flash loans are one of DeFi's most powerful and misunderstood features.

What is a Flash Loan?

A flash loan lets you borrow any amount of cryptocurrency with zero collateral.
The loan must be borrowed, used, and repaid within a single blockchain transaction.
If repayment fails, the whole transaction reverts automatically.

Real Use Cases

Arbitrage between DEXs - buy low on Uniswap, sell high on SushiSwap, repay loan, keep profit
Collateral swaps - swap collateral on Aave without closing your position
Self-liquidation - avoid penalty fees by liquidating your own position
Debt refinancing - move debt between protocols for better rates

Platforms That Support Flash Loans

Aave - most widely used, 0.09% fee
Balancer - 0% fee
Uniswap V3 - called flash swaps

The Honest Reality

Flash loans require real Solidity knowledge, capital for gas fees, and fast execution.
Most arbitrage opportunities close in milliseconds as bots compete.