Payment system is a set of rules, procedures, and technical infrastructure that ensures the transfer of value from one economic entity to another. Payment systems are one of the key components of modern monetary systems.
Payment systems serve as a substitute for cash transactions in conducting domestic and international payments and are one of the basic services provided by banks and other specialized financial institutions.
It is usually implied that money is transferred through payment systems. Legally, in most cases, there is a transfer of debt: the funds that the payment system owes to one client, it becomes owed to another client. When the first client transfers their money to the payment system, the amount of such a transfer is recorded, that is, the amount of debt to the first client. At their discretion, the client can specify that the payment system now owes not to them, but to the second client. When the second client turns to the payment system, they have the opportunity to receive the monetary equivalent of that debt. In some cases, the payment means are not money or debts denominated in money, but conditional payment units or specialized securities (examples include WMR, Bitcoin).