Technological advancement in recent years has compelled central banks to look for new ways to effectively provide payment systems that are fast and more convenient compared to traditional paper-based payment systems. It has led to the birth of the concept of digital currencies issued solely by central banks called Central Bank Digital Currency (CBDC). As this concept is relatively new, there is ongoing research being conducted by several central banks worldwide, and while the research work done thus far has answered many questions, there remains a number of unsettled issues and questions. This paper aims to delve into the literature on this concept and focus on several key questions like the reasons for issuing digital currency, payment systems efficiency, and the advantages and disadvantages of digital currencies issued by central banks. Answering these questions could substantially help figure out the usefulness of creating a new payment method alongside the current payment system. However, extensive future research is required for a comprehensive understanding the effectiveness and usefulness of digital currencies.