Maximal extractable value describes value obtainable through control or influence over transaction inclusion, exclusion, and ordering, beyond ordinary block rewards and transaction fees. Opportunities can arise when one transaction changes a state that another transaction can profitably act on. Searchers identify candidate opportunities, while the block-production pipeline determines what is actually included. The term therefore covers a market structure involving different roles rather than implying that every opportunity is captured directly by a single validator.

An arbitrage transaction can bring inconsistent pool prices closer together after a market move. A sandwich strategy instead places trades around another user's swap, exploiting the victim's permitted execution range. Both involve ordering-sensitive value, but their effects on users differ. A transaction's slippage bound limits acceptable execution, not the ability of observers to notice the pending intent. Understanding the pool's pricing rule and the route through which a transaction reaches a block helps explain where ordering exposure appears.

Private submission, auctions, order-flow protections, and protocol design changes can reduce particular forms of extraction, but each has its own trust, availability, and execution trade-offs. A private relay does not inherently guarantee the best achievable price or complete confidentiality against every participant. Likewise, reducing public mempool exposure does not remove all ordering opportunities at the builder or sequencer level.

Research claims about MEV protection should state the adversary, the protected transaction flow, and what evidence demonstrates the claimed improvement, rather than treating MEV as one uniformly eliminated problem.