A payment network is the electronic infrastructure that connects your bank to a merchant’s bank so a card purchase can be approved and paid. Companies like Visa, Mastercard, American Express, and Discover run these systems, setting the rules every bank and merchant follows and routing the transaction data between them. Visa and Mastercard alone handled nearly $10 trillion in U.S. card purchases in 2025.1Nilson Report. Mastercard and Visa Cards in the US 2025 The design is what lets a card from a small credit union work at a shop on the other side of the world without the two banks ever having met.
A network does not issue cards, hold your money, or lend you credit. It is the wiring and the rulebook. Everything else, including who gets the card, who approves the purchase, and who takes the loss on fraud, sits with the banks on either end.
Who’s Involved in a Card Transaction
Five separate parties touch every card purchase, and knowing who does what makes the rest of the process clear.
- Cardholder. You, the person paying.
- Merchant. The business selling to you. Its terminal or checkout page captures your card data and starts the payment request.
- Acquirer. The merchant’s bank. It submits transactions to the network on the merchant’s behalf and later deposits the funds into the merchant’s account.
- Network. Visa, Mastercard, American Express, Discover, and their peers. The network routes the data and enforces the rules.
- Issuer. Your bank or credit union. It gave you the card, decides whether to approve each purchase, and carries the risk if you don’t pay or if fraud occurs.
The merchant never talks directly to your bank. The acquirer hands the transaction to the network, the network routes it to your issuer, and the answer comes back the same way. That indirection is what makes global card acceptance possible: your issuer and the merchant’s acquirer don’t need any existing relationship, because the network stands between them and guarantees the merchant will be paid once the issuer approves.
How the Money Actually Moves
A single card purchase runs through three phases. The first happens in real time at the register. The other two play out quietly over the next few business days.
Authorization
The moment you tap, dip, or swipe, the merchant’s terminal sends an encrypted request through the acquirer to the network, which routes it to your issuer. Your issuer checks whether the account is active, whether you have the funds or credit available, and whether anything about the purchase looks fraudulent. This normally finishes in well under a second.
If the issuer approves, it returns an authorization code and puts a hold on the funds. No money has moved yet. The hold simply reserves the amount so it can’t be spent twice, and the merchant gets the green light to hand over the goods.
Clearing
At the end of the business day, the merchant batches its approved transactions and sends them to the acquirer. The acquirer forwards the batch to the network, which sorts each item and routes the final details to the right issuer. Clearing is where the numbers become official. If the authorized figure was an estimate — think of a gas pump preauthorization or a restaurant check before the tip — the final amount is locked in here.
Settlement
Settlement is when funds actually change hands. The network nets out what every issuer owes every acquirer across its system and moves the differences. Your issuer transfers the transaction amount, minus an interchange fee, to the merchant’s acquirer. The acquirer takes its own processing cut and deposits the rest into the merchant’s account. Most domestic purchases settle within one to three business days. Cross-border transactions take longer because of currency conversion and additional compliance steps.
Open Loop and Closed Loop Networks
Networks come in two structural flavors, and the difference explains a lot about how fees and acceptance work.
Visa and Mastercard are open loop. The network itself doesn’t issue cards or open accounts. Any bank that meets the network’s certification standards can issue cards or sign up merchants, which is why thousands of banks compete to offer Visa or Mastercard products. Competition drives rewards programs and interest-rate offers, but it also produces a tangle of interchange rates that vary by card type, merchant category, and transaction method. Visa held about 70% of combined Visa-Mastercard U.S. purchase volume in 2025.1Nilson Report. Mastercard and Visa Cards in the US 2025
American Express and Discover started as closed loop networks. In that model, one company issues the card, processes the transaction, and signs up the merchants, keeping the full transaction revenue instead of splitting interchange with a separate issuer. The upside is tighter control over the customer experience and richer data. The historical downside was thinner merchant acceptance, since each merchant had to contract directly with the network. Both Amex and Discover now license other banks to issue their cards, so the line between the two models is not as sharp as it once was.
What Payment Networks Don’t Cover
Not every electronic payment runs on a card network. Two other rails handle enormous volumes of non-card money movement in the United States, and it’s worth knowing where each fits.
ACH
The Automated Clearing House network moves money between U.S. bank accounts for payroll direct deposits, bill payments, tax refunds, and person-to-person transfers. In 2025, ACH processed 35.19 billion payments totaling $93 trillion.2Nacha. ACH Network Volume and Value Statistics
ACH is often described as slow, but that reputation is dated. About 80% of ACH payments settle in one business day or less.3Nacha. The Significant Majority of ACH Payments Settle in One Business Day or Less Debits, where money is pulled from an account, must settle by the next business day under Nacha rules. Credits, where money is pushed to a recipient, can take up to two business days at the sender’s discretion, though most arrive sooner.4Nacha. ACH Payments Fact Sheet Same Day ACH settles up to three times per business day for individual payments of up to $1 million.5Nacha. Same Day ACH The fees are a small fraction of card interchange, which is why employers, utilities, and government agencies lean on it so heavily.
FedNow and RTP
The Federal Reserve launched its FedNow Service on July 20, 2023, creating a real-time payment rail that runs around the clock, every day of the year.6Board of Governors of the Federal Reserve System. FedNow Service Unlike ACH, which processes in batches, FedNow settles each payment individually and instantly. The funds arrive in seconds, with finality; the sender cannot claw them back. The Clearing House operates a private-sector equivalent called Real-Time Payments (RTP). Together, these systems are gradually filling the spots where card networks and ACH fall short, especially where both parties need immediate confirmation that money has landed.
What Merchants Pay to Accept Cards
Every card purchase costs the merchant a fee, and that fee has three parts.
- Interchange fee. The largest slice, set by the network and paid to your issuer. For credit cards, it typically runs from about 1.15% to 3.15% of the transaction amount, depending on card type and merchant category.
- Assessment fee. A smaller charge kept by the network itself to fund its infrastructure and operations.
- Processor markup. The negotiable piece, charged by the processor or acquirer for technology, customer support, and risk management.
Only the processor markup is negotiable. Interchange and assessment are set by the network and non-negotiable for an individual merchant. For a typical credit card purchase, the combined fee usually lands somewhere between 1.5% and 3.5% of the amount.
Debit costs a merchant much less. Under the Federal Reserve’s Regulation II, debit interchange for banks with more than $10 billion in assets is capped at roughly 21 cents plus 0.05% of the transaction.7Board of Governors of the Federal Reserve System. Regulation II (Debit Card Interchange Fees and Routing) Community banks and credit unions under that asset threshold are exempt from the cap.8eCFR. 12 CFR Part 235 – Debit Card Interchange Fees and Routing
How Networks Protect the Transaction
Two layers of security sit under every card purchase: technical protections built into the transaction, and standards every party in the chain has to follow.
When you add a card to Apple Pay, Google Pay, or a similar wallet, the app does not store your real card number. The network replaces your primary account number with a token, a substitute number that works for payments but is useless if stolen.9EMVCo. EMV Payment Tokenisation The token is locked to a specific device or merchant, so intercepting it doesn’t let anyone reuse it elsewhere. Each transaction also generates a one-time cryptographic code, so replaying the same data from an earlier purchase fails. When you tap your phone at checkout, the token and code move through the same authorization, clearing, and settlement path as any card, and the network translates the token back to your real account number before handing the request to your issuer. The merchant never sees your actual card details.
This matters because older magnetic stripe cards broadcast the same static data every swipe, which made counterfeiting straightforward. EMV chip cards alone reduced counterfeit fraud by 76% to 90% in countries that adopted them early.10EMVCo. How Do EMV Chip Specifications Tackle Card Fraud
On top of that, the Payment Card Industry Data Security Standard (PCI DSS) is the baseline every company handling card data must meet. It requires encryption, penetration testing, access controls, and detailed logging. One consequential rule: sensitive authentication data like CVV codes must never be stored after a transaction is authorized, no matter what permission a cardholder might have given.11PCI Security Standards Council. Frequently Asked Question Networks enforce PCI DSS across their ecosystem, and businesses that fail can face fines or lose processing privileges.
When Something Goes Wrong: Disputes and Chargebacks
Federal law and network rules give you a path to reverse a bad charge. Under the Fair Credit Billing Act, you have 60 days from the date your billing statement is sent to notify your card issuer in writing of a billing error.12Office of the Law Revision Counsel. 15 USC 1666 – Correction of Billing Errors The issuer must investigate before it can collect on the disputed amount, and it cannot report the charge as delinquent while the investigation runs.
On the network side, your issuer initiates a chargeback, which pulls the funds back from the merchant’s acquirer. The merchant can respond with evidence that the charge was legitimate, such as a signed receipt or proof of delivery, and the case can escalate to a second review and then to arbitration by the network.13Mastercard. Chargebacks Made Simple Guide
Chargebacks are a strong consumer protection, but they come with limits. Networks track chargeback rates by merchant, and businesses with excessive chargebacks face higher fees or lose the ability to accept cards. Filing frivolous disputes can lead your own issuer to close your account. And the 60-day window is a hard deadline. Miss it and the statutory right to dispute is gone, leaving you to work things out directly with the merchant.