USDD is a decentralized, multi-chain, USD-pegged stablecoin launched by the TRON ecosystem in May 2022 and governed through the TRON DAO Reserve framework. Unlike fiat-backed stablecoins such as USDT or USDC, USDD maintains its $1.00 peg through an over-collateralized reserve model, a Peg Stability Module (PSM) for fixed-rate conversions, and protocol-native liquidation mechanisms. The project has undergone significant architectural evolution, most notably with the launch of USDD 2.0 in January 2025, which shifted the protocol away from a hybrid algorithmic model toward a fully transparent, collateral-backed system.