Layer 2 (L2)

A Layer 2 is a secondary network or protocol built on top of a Layer 1 blockchain, designed to make transactions faster and cheaper while still inheriting the underlying security of the base chain. Rather than processing every transaction directly on the busy and expensive Layer 1, a Layer 2 handles a large volume of activity off-chain, bundles many transactions together, and periodically submits a compressed summary back to the Layer 1 for final settlement.

The core insight is that not every single transaction needs to be immediately processed by thousands of nodes around the world. Many interactions — in gaming, trading, or social applications — can happen quickly and cheaply on a Layer 2, with the Layer 1 serving as the ultimate security backstop. This dramatically increases the number of transactions the overall ecosystem can handle, a property known as “scalability.” Popular Layer 2 networks built on Ethereum include Arbitrum, Optimism, and zkSync. Users can bridge their tokens from Ethereum’s mainnet to one of these Layer 2s, conduct many transactions at a fraction of the cost, and withdraw back to mainnet when needed.

Example: Imagine a busy bank where every transaction — every cup of coffee, every lunch — required a full bank teller and formal paperwork. That would be chaos. Instead, you use a debit card that accumulates your daily spending and settles it against your bank account at the end of the day. Your card is the Layer 2: fast and easy for daily use, but ultimately reconciled with the secure, authoritative bank (the Layer 1) in the background.