Definition
Layer 2 (L2) is a category of blockchain scaling solutions that execute transactions on a secondary network or protocol built on top of a Layer 1 (L1) blockchain—typically Ethereum—then periodically post compressed transaction data or validity proofs back to the L1 for final settlement. The L2 inherits the security of the L1 (transactions settled on L2 are ultimately secured by the L1’s consensus mechanism) while achieving dramatically higher throughput and lower per-transaction costs.
The two dominant L2 architectures are Optimistic Rollups (Arbitrum, Optimism, Base), which assume transactions are valid by default and allow a challenge period for fraud proofs, and ZK Rollups (zkSync, StarkNet, Scroll, Polygon zkEVM), which generate cryptographic validity proofs that mathematically guarantee transaction correctness without requiring a challenge period.
Why It Matters
Ethereum’s Layer 1 processes approximately 15 transactions per second (TPS)—a throughput constraint that, during periods of high demand, pushes gas fees to levels that exclude casual users. In contrast, Layer 2 networks collectively processed an average of 12.5 million transactions per day in Q4 2024 (L2Beat), with individual L2s achieving effective throughput of 2,000-4,000 TPS.
The economics are stark. A simple token transfer on Ethereum L1 costs approximately $1.50-$5.00 in gas during normal conditions. The same transaction on Arbitrum costs $0.01-$0.10. On Base (Coinbase’s L2), costs are often below $0.01 following EIP-4844’s introduction of blob transactions in March 2024, which reduced L2 data posting costs by approximately 90%.
As of early 2026, the total value locked (TVL) across all Ethereum L2s exceeds $40 billion (L2Beat), with Arbitrum ($18B), Base ($8B), and Optimism (~$7B) leading. L2 daily active addresses surpassed L1 active addresses in mid-2024 and have continued to diverge, indicating that user activity is migrating to L2s while L1 serves as the settlement and security layer.
For identity and authentication applications, L2s reduce the cost barrier to on-chain identity operations—decentralized identifiers, verifiable credentials, soulbound tokens—from dollars to fractions of a cent.
How It Works
Layer 2 scaling operates through transaction batching and proof mechanisms:
Transaction execution: Users submit transactions to L2 sequencer nodes. The sequencer orders transactions, executes them against the L2 state, and provides soft confirmations (fast, but not yet settled on L1).
Batching: The sequencer compresses hundreds or thousands of transactions into a single batch. Compression techniques include calldata optimization, state diff encoding, and (post-EIP-4844) blob transactions.
L1 posting: The compressed batch is posted to Ethereum L1 as transaction data (calldata or blobs). This is the primary cost driver for L2 operations.
Proof mechanism:
- Optimistic Rollups: The batch is assumed valid. A 7-day challenge period allows anyone to submit a fraud proof if they detect an invalid state transition. If no fraud proof is submitted, the batch is finalized.
- ZK Rollups: The sequencer generates a zero-knowledge proof that the batch’s state transitions are valid. The proof is verified on L1 by a smart contract. Finality is achieved as soon as the proof is verified (typically minutes, not days).
Bridging: Assets move between L1 and L2 via bridge contracts. Deposits (L1 to L2) are typically processed in minutes. Withdrawals (L2 to L1) take 7 days for Optimistic Rollups (the challenge period) or minutes for ZK Rollups.
Stealth Cloud Relevance
Stealth Cloud’s current authentication via Sign-In with Ethereum is chain-agnostic at the signature level—SIWE verifies wallet signatures regardless of which network the wallet interacts with. However, future governance and identity features may leverage L2 infrastructure for cost-effective on-chain operations.
DAO governance voting, on-chain reputation attestations, and verifiable credential issuance could all execute on an Ethereum L2, where gas costs of $0.001-$0.01 make per-user on-chain operations economically viable at scale. The privacy properties of ZK Rollups are particularly relevant: a zero-knowledge rollup can verify a governance vote is valid without revealing which option the voter selected, aligning with Stealth Cloud’s commitment to privacy by design.
Related Terms
The Stealth Cloud Perspective
Layer 2 makes blockchain economics practical for individual users. When on-chain identity operations cost less than a penny, decentralized authentication stops being an ideological choice and becomes an economically rational default. Stealth Cloud watches this cost curve with precision, because the moment on-chain privacy attestations are cheaper than centralized alternatives is the moment the architecture of the web shifts irreversibly.