The party that orders L2 transactions. A centralized sequencer is fast and is also a censorship point.

The layer that makes transfers final and resolves disputes. For many L2s that layer is Ethereum.

Splitting state or execution across many committees so the network scales beyond one machine.

A sequencer set shared across many rollups to improve censorship resistance and interoperability.

A separate chain with its own validators that bridges assets to a parent chain. Security is independent.

An off-chain agreement where two or more parties update state and only settle the last version on-chain.

OP Stack's vision of many L2s sharing standards, bridges, and governance gravity.