What is Layer 1 (L1)?
A Layer 1 is a base-layer blockchain — Bitcoin, Ethereum, Solana — that provides its own consensus and security. Layer 1s are the settlement layer that other systems (Layer 2s, bridges, dApps) build on top of.
Why Layer 1 (L1) matters
Understanding Layer 1 (L1) 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 1 (L1) 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 2 (L2) — A scaling network that settles to a Layer 1.
- Blockchain — A chained, append-only ledger of blocks.
- Consensus Mechanism — The rules a network uses to agree on the canonical chain.
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.
- Rollup — An L2 that posts transaction data to L1 for security.
- Optimistic Rollup — A rollup that assumes validity, with a fraud-proof challenge window.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.