MEV (Maximal Extractable Value)

MEV, or maximal extractable value, is the profit that whoever builds a block can capture by choosing which transactions to include and in what order. Because pending transactions are usually visible in the public mempool before confirmation, specialised bots scan them for opportunities: arbitrage between exchanges, liquidations, and sandwich attacks that place one trade in front of a large swap and another behind it so the user gets a worse price. Some MEV is benign and keeps markets aligned; the extractive kind is effectively a hidden cost paid through slippage. Users can reduce exposure with tight slippage limits, smaller orders and private transaction relays that keep trades out of the public mempool.