Euler Finance is a non-custodial lending and borrowing protocol on Ethereum that differentiates itself through permissionless asset listing, allowing users to create lending markets for virtually any ERC-20 token. Its innovative features include reactive interest rate models, risk-tiered asset classification (collateral, cross, and isolated tiers), and a unique liquidation mechanism using Dutch auctions to minimize MEV extraction. The protocol relaunched as Euler v2 with a modular architecture, introducing the Euler Vault Kit (EVK) and Ethereum Vault Connector (EVC), enabling composable and customizable lending vaults. This positions Euler as a more flexible infrastructure layer for DeFi lending. However, the protocol suffered a devastating $197M flash loan exploit in March 2023, which remains a significant trust concern despite funds being recovered and security measures being overhauled. The EUL governance token facilitates protocol decision-making but has experienced substantial price depreciation. Euler's technical innovation is commendable, but the exploit history and competitive pressure from Aave and Compound warrant cautious evaluation. The v2 modular approach could be a meaningful differentiator if adoption grows.