MEV
Also called: maximal extractable value, miner extractable value, sandwich attack
MEV is the profit available from reordering, inserting or censoring transactions within a block. The commonest form is the sandwich attack: a bot sees your pending swap, buys ahead of it, and sells into the price you push up. It is front-running made structural rather than illegal, and billions have been extracted — mostly from ordinary users who never knew it happened.