What Is Layer 2 (L2)?
Definition
A Layer 2 is a blockchain built on top of a Layer 1 (like Ethereum) that processes transactions faster and cheaper while inheriting the security of the underlying chain.
L2s solve the scalability problem — achieving speed and low cost without sacrificing security. They process transactions off the main chain but post proofs back to L1 for settlement.
- Optimistic Rollups — Base, Optimism, Arbitrum. Assumes valid, challenges if needed. 7-day withdrawal to L1.
- ZK Rollups — zkSync, StarkNet. Mathematical proofs for instant verification. Faster finality.
Base (Coinbase's L2) is the primary L2 on CoinDevTools: same ERC-20 standard as Ethereum, 10-100x cheaper gas, ~2 second finality, all Ethereum wallets work natively.
Related Terms
Blockchain
A blockchain is a distributed, immutable digital ledger that records transactions across a network of computers — the foundational technology behind all cryptocurrencies and tokens.
Gas (Transaction Fee)
Gas is the fee paid to blockchain validators for processing transactions. On Ethereum it's measured in gwei, on Solana it's called a priority fee — both compensate the network for computation.
ERC-20 Token
ERC-20 is the most widely used token standard on Ethereum and EVM-compatible chains, defining how fungible tokens are created and transferred.
Bridge (Cross-Chain Bridge)
A blockchain bridge is a protocol that transfers tokens or data between two different blockchains — enabling assets created on one chain to be used on another.