The National Payments Corporation of India (NPCI) facilitates e-payment services in India through the Unified Payments Interface (UPI), allowing users to transfer money easily without needing IFSC codes or bank account numbers. UPI offers features like round-the-clock money transfers, secure virtual addresses, and supports multiple bank accounts within a single app, benefitting both customers and merchants. The activation of UPI requires a bank account, mobile number, and a smartphone, making digital transactions more accessible and efficient.