L2 (Layer-2)
L2Layer 2
A scaling network that inherits security from an L1 by posting state roots back — rollups, validiums, plasma.
Ethereum L2s now host the majority of incremental stablecoin yield activity. The dominant security models are Optimistic rollup (7-day fraud-proof window) and ZK rollup (zero-knowledge rollup) (validity proofs, faster finality).
Related terms
- Optimistic rollupAn L2 that posts state roots to L1 and assumes them valid unless a fraud proof is submitted within a challenge window.
- ZK rollup (zero-knowledge rollup)An L2 that posts validity proofs to L1, enabling near-instant withdrawals and stronger trust assumptions than optimistic rollups.
- ArbitrumAn Ethereum optimistic rollup operated by Offchain Labs — the largest L2 by TVL.
- BaseCoinbase's optimistic rollup built on the OP Stack — fastest-growing L2 by stablecoin yield surface.