The advent of digital stablecoins and the continuing decline of cash are prompting central banks across the world to explore developing their own digital currencies. Although few have launched so far, the potential for central bank digital currency (CBDC) promises a revolution in banking. Michael Lloyd considers the opportunities and threats that the arrival of CBDCs will have for commercial banking and the world's monetary system. The choices facing central banks regarding the use, design and technology of digital currencies are examined as well as the potential impacts on consumer security and privacy.