Core Focus: The formal definition of central bank digital currencies, the critical distinction between retail and wholesale CBDCs, and the relationship between CBDCs and the existing two-tier monetary system.

In-Depth Notes:
A Central Bank Digital Currency (CBDC) is a digital liability of a central bank, denominated in the national unit of account, and available to the public or to financial institutions for settlement . It represents the most significant transformation in the form of public money since the transition from physical gold-backed currencies to fiat money. Unlike commercial bank deposits—which are claims on private financial institutions and carry credit risk—CBDCs are direct claims on the central bank and carry no credit or liquidity risk, making them the safest form of digital money .

The Fundamental Taxonomy:
CBDCs are divided into two primary categories based on their intended users. A retail CBDC (rCBDC) is a digital form of central bank money available to the general public for everyday transactions, analogous to physical cash . They are designed to provide a digital payment option that is safe, accessible, and convenient for all citizens, functioning as the digital counterpart to notes and coins . A wholesale CBDC (wCBDC) is restricted to financial institutions for interbank settlement and other wholesale transactions . They are designed to improve the efficiency, speed, and safety of large-value payments and tokenised asset settlement, effectively modernising the technology for interbank transactions . Both retail and wholesale CBDC explorations are advancing, with wholesale projects gaining prominence in recent years . For example, the Hong Kong Monetary Authority has decided to focus development of its e-HKD on wholesale applications because the CBDC has stronger potential value in large transactions than in daily retail use .

The Two-Tier Monetary System and CBDC:
The current monetary system is two-tiered: the central bank issues base money (reserves and physical cash), while commercial banks create broad money through deposit creation and lending. The introduction of a CBDC raises fundamental questions about how this system would operate. Most advanced CBDC projects, such as the European digital euro and China’s e-CNY, are built on a two-tier architecture . In this model, the central bank controls issuance and redemption, while commercial banks and other private sector intermediaries handle distribution, customer-facing services, and the management of user accounts . This design is intended to preserve the role of commercial banks in the financial system and leverage their existing customer relationships, while ensuring that public money remains accessible in digital form. A hybrid/intermediated CBDC—where the private sector plays the role of intermediary with central bank oversight—is the preferred option in most jurisdictions that have launched or are piloting CBDCs . The central question in CBDC architecture is how central bank money should evolve in an increasingly digital financial system and what appropriate role the private sector should play in this evolution .