This article reviews the literature examining how the introduction of a retail central bank digital currency (CBDC) would affect a modern economy, focusing on the implications for the banking sector and for financial stability. A CBDC can improve welfare by reducing financial frictions, countering market power in deposit markets, encouraging financial inclusion, and enhancing the payment system. However, a CBDC also entails noteworthy risks, including the possibility of bank disintermediation and associated contraction in bank credit, as well as potential adverse effects on financial stability. The recycling of the new CBDC liability through asset purchases or lending by the central bank plays an important role in determining the economic consequences of the introduction of a CBDC, raising fundamental questions about the footprint of central banks in the financial system. Ultimately, the effects of a CBDC depend critically on its design features, particularly remuneration.