<aside> 💡 A payment is the transfer of value from one end party—the Sender—to another—the Receiver. We think of three elements involved in a payments transfer: the initiation of the payment, the funding of the payment by the sender, and the delivery of payment to the receiver.
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A payment system connects a large number of end parties, formalizes processes or transfer of value and plays some role in managing risk for the participants.
<aside> ➡️ Click here to navigate to the in depth overview of each payment system.
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There are five core payments systems in the United States:



Estimation from Glenbrook Partners (2015)
Note that wire transfers are excluded. If wire transfers had been included, wire transfers would represent less than 1% of the total “count”, but 93% of the total “amount”—because of the high-value financial market transactions that use wire transfers.

Closed loop vs open loop system - PayPal is technically a closed loop but is generally considered a payments system due to its size. Most payment systems are open loop. Examples include ACH, card and wire transfers. An open loop systems allows for rapid scaling.