Layer 2 (L2)
Layer 2 (L2) is a network on top of a main blockchain (Layer 1). It processes activity on its own and posts a compressed result to the base chain to make transfers cheaper and faster.
How it works
Base chains like Ethereum are secure but can only handle a limited number of transactions, and fees rise at busy times. An L2 bundles hundreds of transactions and writes only a compressed summary to the base chain. The cost of that write is split among everyone, so each person pays less.
The most common type of L2 is the rollup. Optimistic rollups treat a batch as valid unless someone proves otherwise, so withdrawing through their native bridge to the base chain can take about 7 days. ZK rollups attach a cryptographic proof, and withdrawals are usually faster.
L2 security leans heavily on the base chain, but every L2 has its own rules and its own risks: who runs the network, and whether you can exit if it stops. Read how a specific network works before you move money there.
A transfer on the base chain is expensive at peak time. The same transfer inside an L2 costs noticeably less. But to get into an L2 you need a bridge, which is a separate transaction with its own fee and its own risk.
Do not use a bridge from a chat link. Before sending, check that the exchange or wallet on the other side supports this exact network: a wrong network can cost you the whole amount. Bridges are sometimes hacked, so do not move more through them than you can afford to lose.
Questions and answers
What is Layer 2 in simple terms?
It is an add-on network built on top of a blockchain where transfers are cheaper and faster. The results still get recorded on the main chain.
What is the difference between Layer 1 and Layer 2?
Layer 1 is the main blockchain with its own security, like Ethereum or Bitcoin. Layer 2 runs on top of it and relies on its security.
Why does withdrawing from an L2 sometimes take a week?
Optimistic rollups have a challenge period of about 7 days in which errors can be disputed. Third-party bridges are faster, but they charge a fee and add their own risk.
Related terms
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Updated: 2026-10-19