A Layer 1 (L1) blockchain is the foundational network in a blockchain ecosystem. It is the base protocol that validates and finalizes transactions independently without relying on any other network. Bitcoin, Ethereum, Solana, and Avalanche are all examples of Layer 1 blockchains.
Every Layer 1 network has its own consensus mechanism to secure the chain and process transactions. The most common approaches include:
- Proof of Work (PoW) — miners solve complex puzzles to validate transactions, as used by Bitcoin
- Proof of Stake (PoS) — validators lock up tokens as collateral to secure the network, as used by Ethereum
- Other mechanisms — some chains use Delegated Proof of Stake, Proof of History, or hybrid models
The main challenge facing Layer 1 blockchains is the scalability trilemma, which states that a blockchain can only optimize two out of three properties: decentralization, security, and scalability. Bitcoin prioritizes security and decentralization but has limited throughput. Solana optimizes for speed but makes tradeoffs on decentralization.
To overcome scalability limitations, many Layer 1 networks now support Layer 2 solutions that handle transactions off the main chain while still relying on the L1 for final security. Ethereum's rollup-centric roadmap is a prime example of this approach.
When evaluating a Layer 1 blockchain, consider its TVL, developer ecosystem, transaction costs, speed, and how many dApps are built on it.