Front-Running & MEV

Front-running occurs when someone observes a pending transaction and inserts their own transaction before it. In DeFi, this manifests as sandwich attacks: an attacker front-runs a large swap (buying before you) and back-runs it (selling after you), profiting from the price impact. Maximal Extractable Value (MEV) is the total value that can be extracted by reordering, inserting, or censoring transactions. Mitigation strategies: use Flashbots Protect (private mempool), commit-reveal schemes, or protocols with built-in MEV protection.