Payment systems are the indispensable infrastructure for financial markets and business activities. Every commercial trade and financial transaction is finalized only when the final settlement is made through a payment system. If operational failures would occur in a payment system, preventing smooth transfers of funds, national economies and financial markets would be thrown into extreme confusion and seriously damaged. Therefore, the safety and efficiency of payment systems is incredibly important for national economies and financial systems to function effectively. Payment System Technologies and Functions: Innovations and Developments is valuable tool for those interested in learning about payment systems, including academics and researchers, graduate and undergraduate students, relevant parties of authority and central banks, and professionals in payment business who need a complete understanding of payment systems. This reference promotes a better understanding of payment systems and encourages progress on enhancing the safety and efficiency of payment systems.