Your card was approved. Not a cent has moved.

transcript

You tap your card. Approved. The receipt prints. And not a single cent has moved.

Why not move the money at the tap? There are 1 point 19 billion a day. Each one becomes a real bank transfer. Over a billion a day. And money in flight sits inside the network. At risk.

So the tap only asks a question. The network routes it. The cardholder's bank decides. Approved. That's a promise. Tonight, clearing matches the day's sales to their approvals. Each bank's whole day nets to one position. One transfer.

And the promise isn't even the final amount. A restaurant approves 50 dollars. It clears 60, with the tip. A fuel pump holds 100 dollars. And clears 42.

Day T, noon. The tap. Nothing moves. Before midnight, the merchant batches the day's sales. At 2 AM, the network matches and nets every bank. A day or two later, banks that owe wire the money. Then the merchant is paid.

The network never holds the money. It moves messages. Banks move the money. Later, and netted. Approval is a promise. Settlement is the payment.

Full breakdown in the lecture.