Beginner

What Is a Layer 2?

By DappAtlas editors ·

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A layer 2 (L2) is a blockchain network that processes transactions separately from Ethereum and then posts data or proofs back to it, so users pay lower fees while relying on Ethereum for security.

Key takeaways

  • L2s batch many transactions and settle them on Ethereum.
  • Fees on L2s are usually far lower than on Ethereum mainnet.
  • Optimistic rollups (Base, Arbitrum, OP Mainnet) and zk rollups (ZKsync, Scroll, Linea) are the two main types.
  • Moving funds between Ethereum and an L2 uses a bridge.

How a layer 2 works

An L2 runs its own chain, collects transactions into batches and posts them to Ethereum. Anyone can check the batches against Ethereum’s record, which is where the security comes from.[1]

Types of layer 2

Optimistic rollups assume batches are valid and allow a challenge period for fraud proofs. Zero-knowledge (zk) rollups post a cryptographic proof with each batch.[2]

Using a layer 2

You add the network to your wallet with its chain ID and an RPC endpoint, bridge funds from Ethereum and pay gas fees in the L2’s token, usually ETH.

Risks

Bridges are a common target for hacks, and some L2s still rely on a central operator to order transactions. Withdrawals from optimistic rollups through the official bridge can take about a week.[2]

The Bottom Line

An L2 gives you Ethereum-based security at a fraction of mainnet fees. Check which bridge you use and how the network is run.

Educational content, not financial advice.

Gas feeWhat you pay the network to process a transaction.Chain IDThe number that identifies an EVM network.RPC endpointThe URL a wallet or app uses to talk to a blockchain node.
Pros
  • Much lower fees than Ethereum mainnet
  • Uses the same wallets and addresses
Cons
  • Bridging adds steps and risk
  • Official withdrawals from optimistic rollups can take days
Sources (2)
  1. [1] ethereum.org. “Layer 2.” Accessed Sep 26, 2026.
  2. [2] ethereum.org. “Scaling: rollups.” Accessed Sep 26, 2026.
BasicsScaling

Layer 2 FAQ

Is Base a layer 2?

Yes. Base is an optimistic rollup built on the OP Stack that settles to Ethereum.

Do I need a new wallet for a layer 2?

No. EVM wallets such as MetaMask use the same address on Ethereum and its L2s; you only add the network.

How this page works

Sources: ethereum.org, ethereum.org. Data as of Sep 26, 2026.

How we review

Not affiliated with any project listed. Educational content, not financial advice.