The USDD protocol is committed to satisfying consumers' demand for stable digital currencies by allowing them to make electronic payments with USDD. To achieve this, the USDD protocol will be pegged to the USD- the most widely applied fiat currency in the world - to establish a stable, decentralized, and tamper-proof USDD-USD system. The USDD protocol will uncover the nature of currencies and bridge the gap between digital assets and their practical applications.