layer2.wiki

Reef Index

Rollups

Optimistic and ZK rollups that bundle transactions off-chain before settling on Layer 1. The backbone of Ethereum scaling.

core-protocol

State Channels

Off-chain transaction pathways enabling instant finality between participants. Lightning Network and Raiden explored.

scaling

Plasma

Child chains anchored to the root chain via fraud proofs. A pioneering approach to hierarchical scaling.

legacy

Validium

Zero-knowledge proofs with off-chain data availability. Trading decentralization for throughput in controlled environments.

zk-variant

Data Availability

EIP-4844 blobs, Danksharding, and the quest to make rollup data accessible without bloating Layer 1 state.

infrastructure

Bridges

Cross-chain messaging protocols connecting Layer 2s to each other and back to mainnet. Trust assumptions unpacked.

interop

Sequencers

The entities ordering transactions on rollups. Centralized today, decentralizing tomorrow. Shared sequencing on the horizon.

governance

Fraud Proofs

Interactive and non-interactive dispute resolution mechanisms securing optimistic rollups against invalid state transitions.

security

ZK Circuits

Arithmetic circuits, R1CS, and PLONKish constraint systems powering zero-knowledge proof generation for validity rollups.

cryptography

Deep Dive: The Rollup-Centric Roadmap

In late 2020, Vitalik Buterin outlined what would become Ethereum's defining strategic pivot: a rollup-centric roadmap that delegates execution to Layer 2 while the base chain optimizes for data availability and consensus.

This architectural decision transformed Ethereum from a monolithic execution engine into a settlement layer -- a court of final appeal for disputes, a root of trust for proofs, and a bulletin board for compressed transaction data.

The implications ripple outward: rollups compete on execution environments, user experience, and fee structures while inheriting Ethereum's security guarantees. Each rollup is an ocean within an ocean -- a sovereign execution domain tethered to the seabed of Layer 1.

With EIP-4844 introducing blob transactions, and full Danksharding on the horizon, the cost of posting rollup data continues its descent into the abyss. The future is fractal scaling -- Layer 3s atop Layer 2s, each depth adding specialization.