When you tap your card at a checkout or buy something online, a complex series of messages flows between your bank, a card network, a payment processor, and the merchant's bank — all in under two seconds. Understanding this infrastructure helps businesses choose the right payment stack and helps consumers understand why fees exist. This guide maps the full payment processing chain.
The Five Parties in a Card Transaction
Every card payment involves five key parties. The cardholder initiates the payment. The issuing bank (your bank) issued the card and holds your account. The card network (Visa, Mastercard, Amex) sets the rules and routes the transaction. The acquiring bank holds the merchant's account and receives settlement funds. The payment processor is the technology layer between the merchant and the acquiring bank, transmitting authorization requests and settlement data. Some companies serve multiple roles: American Express is both issuer and network; some processors also act as acquirers.
Authorization, Capture, and Settlement
A card payment happens in three stages. Authorization occurs when the merchant's terminal or gateway sends a request to verify that the card is valid and the cardholder has sufficient funds. The issuing bank approves or declines and sends back an authorization code in milliseconds. Capture occurs when the merchant signals the processor to collect the authorized funds — often at end of day for in-store transactions, or immediately for e-commerce. Settlement is the overnight batch process where funds are moved between banks via the card network. The merchant typically receives funds 1–2 business days after settlement.
Interchange, Scheme Fees, and Acquirer Margins
Merchant fees are composed of several layers. Interchange fees are paid to the issuing bank for each transaction — set by the card network and typically 0.5–2% of the transaction. Scheme fees are paid to the card network (Visa, Mastercard). The acquirer margin is the processing company's profit. These three are often bundled into a single "merchant service charge" (MSC). Interchange-plus pricing shows each component separately; flat-rate pricing (like Stripe's 2.9% + $0.30) bundles everything for simplicity. High-volume merchants can negotiate interchange-plus to reduce overall costs.
Payment Gateways and Payment Facilitators
A payment gateway is the software that connects a merchant's website or POS system to the acquirer. Stripe, Braintree, and PayPal are payment facilitators — they bundle gateway, processing, and acquirer services under one contract, significantly reducing the complexity of accepting payments. Traditional acquiring required a separate merchant account with a bank; payment facilitators put merchants on a shared merchant account, enabling instant onboarding but with more risk of account holds. For most online businesses under $1M in revenue, a payment facilitator is the most practical starting point.
Alternative Payment Methods and the Future of Payments
Card rails are being supplemented and in some cases replaced by alternatives. Account-to-account (A2A) payments via open banking bypass card networks entirely. Buy-now-pay-later (BNPL) providers like Klarna and Affirm extend credit at the point of purchase, funded by the merchant's fee rather than the consumer. Real-time payment networks like the UK's Faster Payments, the EU's SEPA Instant, and the US's FedNow settle in seconds 24/7. Stablecoin payments are emerging for cross-border B2B transactions where traditional wire transfers are slow and expensive.
Key Takeaways
- Five parties participate in every card transaction: cardholder, issuer, network, acquirer, and processor.
- Authorization, capture, and settlement are three distinct stages of a card payment.
- Merchant fees consist of interchange (to issuer), scheme fees (to network), and acquirer margin.
- Payment facilitators like Stripe bundle all services for simpler onboarding.
- A2A payments, BNPL, and real-time networks are challenging traditional card rails.
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