What is Layer 2 (L2)?
A Layer 2 is a scaling protocol that processes transactions off the base chain (the Layer 1) and periodically commits batched proofs or data back to it. L2s — rollups, channels, sidechains — inherit security from L1 while offering far higher throughput and lower fees.
Why Layer 2 (L2) matters
Understanding Layer 2 (L2) is part of building a solid mental model of how Bitcoin, blockchain and Web3 systems actually work. Concepts in the Concepts category sit at the foundation of the broader stack — get them right and the rest is far easier.
Learn this interactively
Reading the definition is a start. ZeroToBlock teaches concepts like Layer 2 (L2) through hands-on, browser-based simulations. Build the mental model by actually using it:
- Bitcoin 101 — interactive fundamentals course
- Bitcoin Proof of Work — mining, hashing and consensus
- Browse all interactive blockchain courses
Related terms
- Layer 1 (L1) — A base blockchain network with its own consensus.
- Rollup — An L2 that posts transaction data to L1 for security.
- Lightning Network — Bitcoin's payment-channel scaling layer.
More concepts terms
- Decentralization — Distributing control across many independent participants.
- Atomic Swap — Trustless cross-chain trade using hash time-locked contracts.
- Bridge — A protocol that moves assets or messages between chains.
- Byzantine Fault Tolerance (BFT) — A system that works even when some nodes lie or fail.
- Staking — Locking tokens to secure a network and earn rewards.
- Validator — A node that proposes and attests to blocks in PoS.
- Optimistic Rollup — A rollup that assumes validity, with a fraud-proof challenge window.
- ZK-Rollup — A rollup that proves validity with zero-knowledge cryptography.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.