Layer 2

In the context of cryptocurrency, layer-2 refers to a secondary protocol or framework built on top of an existing blockchain network, designed to address the scalability limitations and high transaction costs of the underlying layer-1 chain. Layer-1 blockchains like Bitcoin and Ethereum are secure and decentralized but can only process a limited number of transactions per second. Layer-2 solutions move much of the transaction processing off the main chain while still inheriting its security guarantees, dramatically increasing throughput and reducing costs.

Some prominent examples of layer-2 solutions include the Lightning Network for Bitcoin, and Optimism, Arbitrum, and Polygon for Ethereum. These solutions use different technical approaches — such as payment channels, rollups, and sidechains — but share the common goal of batching or processing transactions more efficiently before settling the final state back to the main blockchain. Rollups, for example, bundle hundreds of transactions into a single on-chain transaction, spreading the cost across many users and making each individual transaction far cheaper.

Layer-2 technology is increasingly important for the practical usability of blockchain platforms, especially as decentralized finance (DeFi) and NFT markets have driven up demand and gas fees on Ethereum. For traders, layer-2 networks offer faster execution and lower fees, making strategies that involve frequent transactions far more economically viable. Many exchanges and DeFi protocols now offer layer-2 deployments, and algorithmic traders should be aware of the bridging process required to move funds between layer-1 and layer-2 environments, as well as any differences in liquidity and available trading pairs.