Layer 1 blockchains are the foundational networks of the cryptocurrency ecosystem. Every L1 operates its own consensus mechanism, maintains its own validator or miner set, and settles transactions directly on-chain. Bitcoin started it all in 2009 with proof-of-work mining. Ethereum followed in 2015 and introduced programmable smart contracts, creating the foundation for decentralized applications.
The L1 space has since fragmented along clear fault lines: speed versus decentralization, cost versus security, and developer tooling versus battle-tested reliability. Solana processes thousands of transactions per second at sub-cent fees but has faced periodic outages. Cardano prioritizes formal verification and academic rigor but has been slower to build ecosystem momentum. Avalanche uses a novel subnet architecture that lets enterprises run custom chains while sharing the main network's security.
Newer entrants like Aptos and Sui use the Move programming language, originally developed at Meta, to offer parallel transaction execution. Kaspa takes a different approach entirely, using a blockDAG structure instead of a linear chain to achieve high throughput without sacrificing proof-of-work security.
Layer 0 protocols like Cosmos and Polkadot sit beneath individual L1s, providing shared security and cross-chain communication. Cosmos uses the Inter-Blockchain Communication (IBC) protocol, while Polkadot connects parachains through its relay chain. Both aim to solve the fragmentation problem: the reality that assets and data remain siloed across competing L1 networks.
The key metrics that distinguish L1 blockchains are throughput (transactions per second), finality time (how fast a transaction becomes irreversible), fees, and total value locked (TVL) in their DeFi ecosystems. Ethereum still dominates TVL by a wide margin, but chains like Solana, Avalanche, and Sui have carved out significant niches in areas like payments, gaming, and real-world asset tokenization.