Sequencer
The sequencer is the operator that orders transactions on a rollup — collecting user transactions, executing them, and posting batches to Ethereum. Today n
The sequencer is the operator that orders transactions on a rollup — collecting user transactions, executing them, and posting batches to Ethereum. Today nearly every major rollup runs *one* centralized sequencer, making it the system’s most obvious choke point.
Why it matters
A single sequencer can theoretically censor, reorder for MEV, or halt the chain by going offline (users can usually force-exit via L1, slowly and painfully). Decentralizing sequencers — shared sequencing networks, based rollups — is the industry’s acknowledged hardest remaining problem, and the main reason rollup infrastructure scores stay capped.