Card networks
A card network is a rulebook and a switch. Visa and Mastercard do not lend anyone money, do not hold anyone's account, and do not decide whether your payment is approved. They define what the messages mean, move them between banks, price the transaction, and settle the net positions at the end of the day.
Almost every deadline, fee name and dispute right in this primer originates here. That is what makes the network worth understanding even though you will never speak to one.
Four parties, not two
The structure that makes cards work is that the buyer's bank and the seller's bank do not need a relationship with each other. They each have one with the network.
Every bank joins once and can then transact with every other member. This is the four-party model, and it is the reason a card issued by a small bank in one country works at a terminal on the other side of the world.
American Express and Discover historically ran a three-party model instead, issuing the card and acquiring the merchant themselves. The distinction still shows up in practice: a closed-loop network sets its own pricing without an interchange schedule, because there is no second bank to pay. Both now also issue through partner banks, so the neat split is blurrier than it once was.
What the network actually does
- Switches the message. It routes authorization requests to the right issuer and the responses back to the right acquirer, in well under a second.
- Publishes the rules. Authorization deadlines, capture windows, reversal obligations, dispute rights and evidence standards are all scheme rules. Authorization and disputes both run on them.
- Sets the interchange schedule. The network decides which category a transaction falls into and therefore what interchange applies. It does not receive that money — interchange goes to the issuer.
- Charges its own fees. These are the assessments described in clearing and settlement, and they are the network's actual revenue.
- Calculates and settles net positions. Members owe each other a single figure per day, not one per transaction.
- Decides arbitration. When an issuer and an acquirer cannot agree on a dispute, the network rules on it and charges the loser.
- Approves on the issuer's behalf when the issuer is unreachable. Stand-in processing keeps payments working through an issuer outage, within limits the issuer sets in advance.
Why escalating to the network almost never helps
The network is a party to your transactions and not to your contract. It has no visibility of your merchant account, no control over when your provider pays you, and no relationship with you at all — your relationship runs through your acquirer.
So the split is worth learning as a routing rule for your own escalations. If the problem is a rule, a deadline, or a dispute right, the network defined it and your acquirer can tell you what it says. If the problem is money not arriving, the network has nothing to do with it. Funding makes the same point from the other end: funding delays are commercial, and there is nobody at Visa to call about them.
Terms introduced
- Four-party model — issuer, acquirer, network and merchant, with the two banks connected only through the network.
- Three-party model — a closed loop where one company both issues the card and acquires the merchant.
- Scheme rules — the network's published rulebook, which sets deadlines, dispute rights and evidence standards.
- Interchange schedule — the network's published table assigning each transaction category its interchange rate.