Layer 1
The foundational blockchain layer where transaction settlement and security occur.
Layer 1 (L1) represents the underlying infrastructure of a blockchain network like Bitcoin, Ethereum, or Solana. It is a self-sufficient network that manages the ledger, validates transactions, and maintains the shared state of the protocol. L1 defines the primary rules (consensus) and parameters (block time/size). When L1 networks reach capacity, Layer 2 scaling solutions are built 'off-chain' to handle high transaction volumes while periodically anchoring their state to the L1 for decentralized security and finality.
graph LR
Center["Layer 1"]:::main
Pre_blockchain_basics["blockchain-basics"]:::pre --> Center
click Pre_blockchain_basics "/terms/blockchain-basics"
Pre_cryptography["cryptography"]:::pre --> Center
click Pre_cryptography "/terms/cryptography"
Rel_layer_2["layer-2"]:::related -.-> Center
click Rel_layer_2 "/terms/layer-2"
Rel_avalanche["avalanche"]:::related -.-> Center
click Rel_avalanche "/terms/avalanche"
Rel_blockchain_basics["blockchain-basics"]:::related -.-> Center
click Rel_blockchain_basics "/terms/blockchain-basics"
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🧒 Explain Like I'm 5
🌍 Think of Layer 1 as the land and the bedrock of a city. It's the foundation that holds everything else up: you can build skyscrapers (L2 apps) on top, but the strength of the entire system depends on the [solidity](/en/terms/solidity) of the ground.
🤓 Expert Deep Dive
Layer 1 protocols solve the 'Blockchain Trilemma'—the balance between security, scalability, and decentralization. In monolithic architectures, consensus, data availability (DA), and execution happen on the same layer. Modern modular L1 designs separation these functions to increase throughput. L1s act as the 'trust anchor' for Layer 2 solutions, providing the finality and security proof required for cross-layered ecosystems.