Maximal extractable value (MEV) refers to the value that can be extracted from block production by including, excluding, and changing the order of transactions in a block. For decentralized application developers, preventing smart contracts from being extracted is essential. On the other hand, smart contracts can offer MEV under certain circumstances to leverage block producers/miners to provide service.
Some use cases of MEV: NFT mint war, smart contract keeper, gasless/meta transaction.
Ethereum DApp developer