Ethereum Layer 2: A Simplified Overview

Zach Anderson   Sep 12, 2023 13:04 3 分钟阅读

Common Ethereum Layer 2 projects include Optimism, Arbitrum and zkSync. Tokens from some of these projects, such as ARB (Arbitrum) and OP (Optimism), have been available for trading. This article aims to explain the concept of Layer 2 in straightforward terms.

As blockchain technology continues to evolve, Ethereum has established itself as a leader in smart contracts and decentralized applications. However, its growing popularity has brought about challenges, particularly in terms of scalability and transaction costs. To address these issues, Layer 2 (L2) solutions were introduced, designed specifically to navigate these hurdles.

What is Layer 2 (L2)?

Layer 2, often abbreviated as L2, refers to a secondary framework or protocol built atop the existing blockchain (Layer 1 or L1). The primary objective of L2 solutions is to increase transaction throughput and reduce associated costs, all while maintaining the security and decentralization properties of the main chain.

The Basics: Layer 1 vs. Layer 2

Layer 1 (L1) is the foundational blockchain layer. Think of Ethereum or Bitcoin; these are L1 blockchains. They form the bedrock upon which L2 solutions are constructed. L1 handles the core consensus, maintains the network's security, and records all transactions.

Layer 2 (L2), on the other hand, operates atop L1 and can process transactions off-chain or in a more scalable manner. The results are then settled back onto the main chain, ensuring the security and immutability of the primary blockchain.

The Promise of Layer 2

Lowered Transaction Costs: L2 solutions, by handling numerous transactions off-chain and consolidating them into one L1 transaction, can markedly decrease the expense of each transaction.

Improved Transaction Capacity: Compared to conventional L1 blockchains, L2 solutions are capable of processing a greater volume of transactions every second (TPS), tackling a primary concern in the world of cryptocurrency.

Maintained Security: Even though transactions might be processed off-chain, they eventually settle on the main chain, inheriting the security properties of L1.

Diving Deeper: Types of Layer 2 Solutions

1. Rollups: These are a popular L2 solution where transactions are processed off-chain and then bundled or "rolled up" into a single transaction that's recorded on L1. There are two main types of rollups:

Optimistic Rollups: Transactions are assumed to be valid unless proven otherwise. If a transaction appears suspicious, it can be challenged and verified.

Zero-Knowledge Rollups (ZK-Rollups): These use cryptographic proofs to validate transactions off-chain. Only the proof, which is much smaller in size, is submitted to L1.

2. State Channels: These are off-chain corridors where multiple transactions can occur between participants. Once the series of transactions is complete, the final state is settled on the main chain.

3. Plasma: A framework that allows for the creation of child chains branching from the main chain. These child chains can operate independently and report back to the parent chain periodically.

Layer 2 in Action

Several projects are pioneering the L2 space:

Arbitrum: An Optimistic Rollup solution aiming to make Ethereum transactions more cost-effective.

Optimism: Another Optimistic Rollup, focusing on scaling Ethereum and enhancing its overall efficiency.

zkSync: A ZK-Rollup platform that offers a scalable, low-cost solution for Ethereum transactions.


Layer 2 solutions represent a promising step forward in addressing the scalability and cost issues associated with current blockchain networks. As these solutions continue to evolve and mature, they could pave the way for broader adoption of blockchain technologies and a more efficient decentralized future.

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