Layer 2

A secondary framework built on top of a Layer 1 blockchain to improve scalability.

Layer 2 (L2) refers to secondary frameworks or protocols built on top of an existing Layer 1 blockchain to improve its scalability and efficiency. L2 solutions process transactions off the main chain while still leveraging the security of the underlying L1.

Types of Layer 2 Solutions

Optimistic Rollups: Assume transactions are valid by default and only run computation in case of disputes (Arbitrum, Optimism, Base).

ZK-Rollups: Use zero-knowledge proofs to verify transaction validity (zkSync, StarkNet, Polygon zkEVM).

State Channels: Off-chain channels for direct transactions between parties (Lightning Network for Bitcoin).

Benefits

Layer 2 solutions dramatically reduce transaction costs, increase throughput (transactions per second), and decrease confirmation times while maintaining the security guarantees of the underlying Layer 1.

Popular Layer 2s

On Ethereum: Arbitrum, Optimism, Base, zkSync, StarkNet, Polygon zkEVM. On Bitcoin: Lightning Network, Stacks.

Frequently Asked Questions

What is a Layer 2 solution?

A Layer 2 (L2) solution is a protocol built on top of a base blockchain to improve scalability. L2s process transactions off the main chain, then settle results on L1, achieving higher throughput and lower costs while inheriting L1 security.

What are the best Layer 2 networks?

Leading Ethereum L2s include Arbitrum, Optimism, and Base (optimistic rollups) and zkSync and StarkNet (ZK-rollups). For Bitcoin, the Lightning Network is the primary L2. Each offers different tradeoffs in speed, cost, and compatibility.

How do Layer 2 rollups work?

Rollups bundle hundreds of L2 transactions into a single compressed batch posted to L1. Optimistic rollups assume validity and allow fraud challenges; ZK-rollups generate mathematical proofs that verify batch correctness without re-execution.