At peak congestion in 2021, sending $20 of Ethereum could cost $60 in gas fees. That broke something important: if fees exceed the amount you are moving, the network has failed at being useful money.
Layer 2 networks were built to fix that. Here is what they actually are and how they work.
The Problem with Layer 1
The main blockchain -- Ethereum, Bitcoin, and others -- is called Layer 1 (L1). These chains prioritize security and decentralization. Every transaction is verified by thousands of nodes worldwide before being finalized. That process takes time, and the block space that handles transactions is limited.
When demand spikes, users bid higher fees to get their transactions included faster. The result: fees go up, often dramatically, pricing out smaller transactions entirely.
Bitcoin's answer to this is the Lightning Network. Ethereum's answer is a category of scaling solutions called Layer 2.
What Is a Layer 2 Network?
A Layer 2 (L2) is a separate blockchain that sits on top of an L1 and processes transactions off the main chain. It then periodically posts a compressed summary of those transactions back to Layer 1 to inherit its security.
The key insight: if you can batch thousands of transactions into a single on-chain settlement, the cost per transaction drops dramatically. Users get fast, cheap interactions while the main chain remains the ultimate source of truth.
Types of Layer 2 Solutions
There are two main technical approaches used by most Layer 2 networks today:
Optimistic Rollups -- These assume transactions are valid by default and only run fraud proofs if someone challenges a transaction. Arbitrum and Optimism use this approach. Withdrawals back to Layer 1 typically take 7 days due to the challenge window, though bridges exist to speed this up.
ZK Rollups -- These generate cryptographic proofs (zero-knowledge proofs) that mathematically verify the validity of every transaction batch. Faster finality, stronger guarantees, but more computationally intensive to generate. zkSync and Polygon zkEVM use this approach.
The Major Layer 2 Networks on Ethereum
- Arbitrum: The largest Ethereum L2 by total value locked. Used by major DeFi protocols including Uniswap and GMX
- Optimism: Powers the OP Stack, a framework that Coinbase's Base chain also uses
- Base: Built by Coinbase on the OP Stack. Fast growing with a focus on onboarding new users to crypto
- zkSync Era: ZK rollup with high throughput and growing DeFi ecosystem
- Polygon: Multiple scaling solutions including their own ZK rollup; widely used for gaming and NFTs
How Much Cheaper Is It?
On Ethereum mainnet, a simple token swap might cost $5 to $50+ depending on congestion. On Arbitrum or Base, that same swap typically costs under $0.10. For DeFi users moving funds frequently, this difference is significant.
Speed also improves substantially. Ethereum finalizes blocks roughly every 12 seconds. Most L2s confirm transactions in under 2 seconds.
Using Layer 2 Networks
To use an L2, you bridge your funds from Ethereum to the Layer 2 using an official bridge or a cross-chain swap service. Once your funds are on the L2, you interact with it using the same wallet (MetaMask, for example) -- you just switch to the L2 network in your wallet settings.
If you want to move funds between chains without the native bridge delays, non-custodial swap services like ChangeNOW support cross-chain swaps across multiple networks. You send on one chain and receive on another in minutes, without creating an account.
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Should You Be Using Layer 2?
If you interact with Ethereum-based DeFi, NFTs, or on-chain applications, yes. The cost and speed improvements are real and the security tradeoffs are minimal for most use cases.
If you mostly hold Bitcoin and check your wallet once a month, you probably do not need to think about this yet. But as crypto applications get more sophisticated, most activity is moving to Layer 2s. Understanding how they work will help you navigate where things are heading.