DeFi TVL: Ethereum DeFi TVL is $50B+ (Feb 2026). If you're quoting numbers from 2023-2024, they're stale.
Uniswap V4 is live. Launched mainnet January 31, 2025 on 10+ chains. V4 introduced a hooks system — custom logic attached to pools (dynamic fees, TWAMM, limit orders, custom oracles). This is the biggest composability upgrade since flash loans. PoolManager addresses are different per chain (NOT deterministic like V3).
Costs changed everything: A flash loan arbitrage on mainnet costs $0.05-0.50 in gas now (was $5-50). This opens composability patterns that were previously uneconomical.
DeFi legos and protocol composability on Ethereum and L2s. Major protocols per chain — Aerodrome on Base, GMX/Pendle on Arbitrum, Velodrome on Optimism — plus mainnet primitives (Uniswap, Aave, Compound, Curve). How they work, how to build on them, and how to combine them. Use when building DeFi integrations, choosing protocols on a specific L2, designing yield strategies, or composing existing protocols into something new. Source: austintgriffith/ethskills.