KoinlyticsMiners, validators, and sequencers all decide transaction order. They live on different chains, get paid differently, and have different attack surfaces. Confusing them is a common source of misunderstanding.
Miner (PoW)
- Chain: Bitcoin, Litecoin, older Ethereum.
- Selected by: hashrate (computation).
- Paid by: block subsidy + tx fees.
- Bond: hardware capex.
- Attack: acquire >50% hashrate (billions of dollars).
Validator (PoS)
- Chain: Ethereum, Solana, Cosmos, Sui, Cardano.
- Selected by: stake weight.
- Paid by: issuance + tx fees + MEV.
- Bond: stake (slashable).
- Attack: acquire >33% stake (Byzantine fault liveness) or >66% (safety).
Sequencer (rollup)
- Chain: L2 rollups (Arbitrum, Optimism, Base, StarkNet).
- Selected by: rollup governance (single sequencer today; decentralization roadmap).
- Paid by: users' L2 gas + MEV.
- Bond: none (yet).
- Attack: sequencer misbehavior = censorship (users can force-exit via L1 in emergency).
What each has in common
- All can reorder transactions in their block (MEV extraction).
- All can censor transactions (miner mempool filter, validator blacklist, sequencer inclusion policy).
- All are subject to some form of decentralization vs efficiency tradeoff.
Where the industry is heading
- Miners stay on Bitcoin. Ethereum PoS proved you can drop them.
- Validators everywhere else. Set size varies from ~150 (some Cosmos chains) to 900k+ (Ethereum).
- Sequencers eventually decentralized via shared sequencing (Espresso, Astria) or per-rollup elections.