BREAKING
Bitcoin Absorbs $1.42B in Single-Day Spot ETF Inflows as Global Central Banks Expand Liquidity
InfrastructureLetter: L

What is Layer 2 (L2)?

Definitive Definition

A Layer 2 (L2) is a secondary protocol built on top of a base Layer 1 blockchain (such as Ethereum) designed to significantly increase transaction throughput and lower fees by processing transactions off-chain and settling compressed cryptographic proofs back to Layer 1.

In-Depth Architectural & Economic Analysis

Layer 2 solutions scale blockchains without compromising the underlying Layer 1 decentralized security or data availability. Major implementations include Optimistic Rollups (Arbitrum, Optimism, Base) and Zero-Knowledge Rollups (zkSync, Starknet, Scroll), utilizing EIP-4844 data blobs for cost-effective settlement.

Core Characteristics & Mechanism

  • Off-chain execution with on-chain cryptographic settlement.
  • Reduces transaction fees by 90%–99% compared to base Layer 1.
  • Inherits the complete censorship-resistance and security guarantees of the L1.
  • Enables thousands of transactions per second (TPS).
Practical Application Scenario:

Arbitrum processes decentralized derivatives trades for less than $0.01 per execution while posting batched state roots securely to Ethereum mainnet.

Related Glossary Entries in Infrastructure

Blockchain
A blockchain is a distributed, immutable digital ledger of cryptographically linked blocks of data shared across a peer-to-peer network of computer nodes. Each block contains a cryptographic hash of the previous block, a timestamp, and verified transaction records, preventing retrospective alteration.
Gas Fee
A gas fee is the transaction fee paid by a crypto user to network validators or miners to compensate them for the computational power required to process, validate, and execute transactions or smart contracts on a blockchain network like Ethereum.
Node (Full Node)
A full node is a computer connected to a blockchain network that downloads, stores, and independently validates every block and transaction against the consensus protocol rules, maintaining a complete, real-time copy of the distributed ledger.