Layer 0, Layer 1, and Layer 2 in crypto/blockchain architecture
Layer 0 (Foundation Layer)
- What it is: The underlying infrastructure that makes blockchains possible.
- Function: Provides the network, hardware, and protocol base that different blockchains (Layer 1s) can be built on.
- Key Features:
- Focuses on interoperability (different blockchains communicating).
- Provides scalability and security frameworks for Layer 1s.
- Often includes SDKs or frameworks for building blockchains.
- Examples: Polkadot (with its relay chain + parachains), Cosmos (with Tendermint + IBC), Avalanche Subnets.
Layer 1 (Base Blockchain Layer)
- What it is: The main blockchain itself — the protocol where transactions are validated, blocks are produced, and consensus is reached.
- Function: Acts as the core ledger and consensus engine.
- Key Features:
- Defines block structure, consensus (PoW, PoS, etc.), and tokenomics.
- Can host smart contracts and dApps (if designed for it).
- Limited scalability without extra help.
- Examples: Bitcoin, Ethereum, Solana, Cardano, BNB Chain.
Layer 2 (Scaling Layer)
- What it is: Built on top of a Layer 1 blockchain to improve speed, cost, and scalability while still relying on Layer 1 for security.
- Function: Takes some of the load off Layer 1 by handling transactions off-chain or in parallel, then settling final states back on the base chain.
- Key Features:
- Faster & cheaper transactions.
- Inherits the security of Layer 1.
- Uses techniques like rollups, sidechains, or payment channels.
- Examples: Polygon (on Ethereum), Arbitrum, Optimism, Lightning Network (on Bitcoin).
✅ In simple terms:
- Layer 0 = the internet cables + framework for building blockchains.
- Layer 1 = the blockchain itself (Ethereum, Bitcoin, etc.).
- Layer 2 = speed boosters built on top to make transactions cheaper and faster.
| Feature | Layer 0 | Layer 1 | Layer 2 |
|---|---|---|---|
| Definition | Foundational infrastructure for creating and connecting blockchains | Base blockchain protocol where transactions are validated and recorded | Scaling solutions built on top of Layer 1 |
| Main Role | Provides interoperability, networking, and framework to build blockchains | Acts as the main ledger & consensus layer | Improves scalability, speed, and lowers transaction costs |
| Security | Provides framework but relies on Layer 1 chains for execution | Secures transactions through native consensus (PoW, PoS, etc.) | Inherits security from the underlying Layer 1 |
| Scalability | Offers tools to build scalable Layer 1s | Limited by block size, throughput, and consensus | High scalability by offloading transactions |
| Examples | Polkadot, Cosmos, Avalanche Subnets | Bitcoin, Ethereum, Solana, Cardano | Lightning Network, Polygon, Arbitrum, Optimism |
| Users Interact With | Rarely directly (mostly for developers building chains) | Directly, via wallets, exchanges, dApps | Indirectly, usually via apps/wallets that integrate L2 (cheaper tx) |