Overview
A sequencer is the actor that orders and batches transactions on a rollup before posting them to the base layer. It determines transaction order and fee collection. Sequencers are central to Layer 2 architecture.
How It Works
The sequencer receives transactions, orders them, and produces batches that are posted to the base chain. It provides fast, cheap transaction confirmation. Decentralized sequencer designs distribute this role.
Why It Matters
Sequencers give rollups their speed and low fees, but centralized sequencers are a trust and liveness concern. Decentralizing sequencing is an active research area. Understanding sequencers is key to L2 evaluation.
Related Concepts
Sequencers are central to Rollups and Layer 2, relating to Batches and Data Availability. They connect to Proposers and consensus.