Term
MEV (Maximum Extractable Value)
MEV (Maximum Extractable Value, originally Miner Extractable Value) is the profit that block producers or "searchers" extract by reordering, inserting, or censoring transactions within a block — front-running, sandwich attacks, and arbitrage all fall under MEV.
MEV is the value that whoever produces the next block on a blockchain can extract beyond the standard block reward and transaction fees, by choosing which transactions to include and in what order. On Ethereum, "searchers" scan the mempool for profitable opportunities (arbitrage between DEXes, liquidations on lending protocols) and pay validators to include their own transactions in the right position.
The negative-sum forms of MEV are front-running (executing a copy of a victim's pending transaction ahead of it) and sandwich attacks (buying an asset just before a large user swap moves the price, then selling immediately after). These extract value directly from ordinary users' trades.
Mitigations exist but are imperfect. Private mempools (Flashbots Protect, MEV Blocker) route your transaction to validators without broadcasting it publicly, hiding it from searchers. On DEX trades, slippage tolerance controls how much sandwich attacks can extract. On chains with different execution models (Solana, others), MEV takes different forms.
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