Layer 2
What is Layer 2?
Layer 2A scaling network that processes transactions off-chain while inheriting security from a base Layer 1 blockchain such as Ethereum or Bitcoin.
A Layer 2 (L2) blockchain is built on top of a Layer 1 (L1) settlement chain and is designed to provide cheaper, faster, or more programmable transactions while relying on the L1 for finality and security. Common L2 architectures include optimistic rollups (Optimism, Arbitrum, Base), ZK-rollups (zkSync, StarkNet, Polygon zkEVM, Linea), state channels (Lightning Network on Bitcoin), and validiums. L2s post calldata or proofs to the L1 so that anyone can reconstruct state or contest invalid transitions. From a security standpoint, defenders must consider sequencer centralisation, bridge risk between L1 and L2, fraud-proof or validity-proof correctness, and the fact that smart-contract vulnerabilities exist at both layers.
● Examples
- 01
A user pays on Base (Coinbase's OP-stack L2) at a fraction of Ethereum mainnet gas.
- 02
Arbitrum One settles batches to Ethereum with a 7-day fraud-proof window.
● Frequently asked questions
What is Layer 2?
A scaling network that processes transactions off-chain while inheriting security from a base Layer 1 blockchain such as Ethereum or Bitcoin. It belongs to the Web3 & Blockchain category of cybersecurity.
What does Layer 2 mean?
A scaling network that processes transactions off-chain while inheriting security from a base Layer 1 blockchain such as Ethereum or Bitcoin.
How does Layer 2 work?
A Layer 2 (L2) blockchain is built on top of a Layer 1 (L1) settlement chain and is designed to provide cheaper, faster, or more programmable transactions while relying on the L1 for finality and security. Common L2 architectures include optimistic rollups (Optimism, Arbitrum, Base), ZK-rollups (zkSync, StarkNet, Polygon zkEVM, Linea), state channels (Lightning Network on Bitcoin), and validiums. L2s post calldata or proofs to the L1 so that anyone can reconstruct state or contest invalid transitions. From a security standpoint, defenders must consider sequencer centralisation, bridge risk between L1 and L2, fraud-proof or validity-proof correctness, and the fact that smart-contract vulnerabilities exist at both layers.
How do you defend against Layer 2?
Defences for Layer 2 typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Layer 2?
Common alternative names include: L2, Layer 2 network.
● Related terms
- web3№ 1268
ZK-Rollup
A Layer 2 scaling technique that batches transactions off-chain and posts a succinct zero-knowledge proof of their validity to the underlying Layer 1 blockchain.
- web3№ 300
DeFi
Decentralized Finance: financial protocols built from smart contracts on public blockchains that offer lending, trading, and other services without traditional intermediaries.