What are Layer 2 blockchains and how do they work?

Layer 1 blockchains like Bitcoin and Ethereum are powerful, but they have limits. As more people use them, transactions slow down and fees climb. Layer 2 networks were built to solve that problem.

This guide explains what Layer 2 is, how it works, the main frameworks, and why Layer 1 and Layer 2 need each other.

What is a Layer 2?

A Layer 2 (L2) is a secondary network built on top of a base blockchain, known as Layer 1. It handles transactions separately, then settles the final results back on the main chain.

The goal is scalability. Layer 1 blockchains process every transaction on-chain, which limits how many they can handle at once. Layer 2 moves most of that activity off the main chain, processes it more efficiently, and uses the main chain only for final settlement. The result is faster transactions and lower fees, without changing the underlying Layer 1 protocol.

Ethereum has the most active Layer 2 ecosystem. Networks like Arbitrum, Optimism, and Base all sit on top of Ethereum, inheriting its security while enabling faster and cheaper activity. If you are newer to how crypto networks are structured, the CoinTracker guide to trading crypto for beginners covers useful background.

How do Layer 2 networks operate?

Layer 2 networks work by batching or processing transactions outside the main chain, then submitting a compressed summary back to Layer 1 for verification and final settlement.

Here is a simplified version of the process:

• A user initiates a transaction on the Layer 2 network.
• The transaction is processed on Layer 2, which is faster and cheaper than Layer 1.
• A batch of transactions is bundled together and submitted to Layer 1 as a single record.
• Layer 1 verifies the batch and records the final state.

This batching approach is what makes Layer 2 efficient. Instead of each transaction occupying space on the main chain, hundreds or thousands can be compressed into a single on-chain entry.

What are Layer 2 frameworks?

The most widely used Layer 2 framework today is rollups. There are two main types.

Rollups

Rollups execute transactions off-chain, bundle them into batches, and submit compressed data back to Layer 1.

Optimistic rollups

Optimistic rollups assume transactions are valid by default and submit them to Layer 1 without immediate verification. A challenge period, typically around 7 days, allows anyone to dispute a transaction if they believe it is fraudulent. If no challenge is raised, the transaction is finalized.

This approach is computationally efficient because verification only happens when disputes arise. Arbitrum and Optimism are examples of optimistic rollup networks.

ZK rollups

Zero-knowledge (ZK) rollups generate a cryptographic proof for every batch of transactions. This proof, called a validity proof or ZK-SNARK, mathematically confirms that all transactions in the batch are valid before the batch is submitted to Layer 1.

ZK rollups finalize faster than optimistic rollups because there is no challenge period. zkSync and StarkNet are examples of ZK rollup networks.

Advantages of Layer 2 solutions

Layer 2 networks offer several practical benefits for people using crypto.

• Higher transaction throughput. Layer 2 networks can process many more transactions per second than their underlying Layer 1 chains. By handling transactions off the main chain and batching them, they remove the bottleneck that limits scalability.
• Reduced transaction costs. Fees on Layer 2 networks are typically a fraction of what they are on Layer 1. Batching hundreds of transactions into a single on-chain record spreads the cost across all of them, making small transactions practical in a way that is often not viable on the main chain.
• Faster transaction finality. Transactions on Layer 2 confirm in seconds rather than the minutes it can take on Layer 1. For day-to-day use cases like payments or gaming, that speed difference matters.
• Improved privacy. Some Layer 2 frameworks, particularly ZK rollups, use cryptographic proofs that can limit how much transaction detail is visible on the main chain. This gives users more privacy without compromising the security guarantees of Layer 1.
• Application-specific flexibility. Layer 2 networks can be designed with specific use cases in mind, from decentralized finance (DeFi) to gaming to payments. This specialization lets developers optimize for the needs of their users rather than the constraints of a general-purpose Layer 1.

What is the difference between Layer 1 and Layer 2?

Layer 1 and Layer 2 serve different roles in the blockchain stack.

Layer 1 is the base blockchain: Bitcoin, Ethereum, Solana, and similar networks. It is the foundation where all final transaction records are stored and where consensus is reached. Layer 1 is what gives the overall system its security and decentralization. The tradeoff is throughput. Processing every transaction directly on the main chain limits how many the network can handle at once.

Layer 2 is a secondary framework built on top of Layer 1. It handles transaction processing separately, then settles results back to the main chain. Layer 2 does not change how Layer 1 works. It works alongside it, using Layer 1 as a trust anchor while enabling far greater scalability and lower fees.

Think of Layer 1 as the main road and Layer 2 as an express lane that handles most of the traffic, merging back when needed.

Why both Layer 1 and Layer 2 scaling solutions are important

Neither layer makes the other redundant. They are designed to work together.

Layer 1 matters because it is the source of security and finality. Every Layer 2 network ultimately depends on the Layer 1 it is built on to verify and record final states. Without a secure, decentralized base layer, Layer 2 networks would have nothing to inherit their trust from.

Layer 2 matters because it solves the scaling bottlenecks that make Layer 1 impractical for high-volume use. Without Layer 2, the cost and speed of using crypto for everyday transactions would remain prohibitive for most people.

Beyond scaling, Layer 2 networks also support application-specific needs. Some projects build dedicated Layer 2 chains, called appchains, designed specifically around the requirements of a single application or ecosystem. This lets developers tune performance, fees, and governance for their users without needing to modify the underlying Layer 1.

Together, Layer 1 and Layer 2 create a more capable and accessible system than either could deliver alone.

From tracking to taxes: how CoinTracker streamlines your crypto journey

As crypto activity spreads across Layer 1 and Layer 2 networks, keeping track of your transactions gets more complex. CoinTracker lets you sync wallets across multiple chains, automatically organizes your transaction history, and helps you generate tax forms when you need them.

Whether you are active on Ethereum, using a Layer 2 like Arbitrum or Base, or holding across several chains, CoinTracker brings it into one place so you spend less time organizing and more time focused on what matters.

Disclaimer: This post is informational only and is not intended as tax advice. For tax advice, please consult a tax professional.