The merchant's bank. They handle card transactions on behalf of businesses, routing them to the network and collecting funds after settlement.

Founded in 1850 as an express mail business, Amex pivoted to financial services and now operates as both a card network and a bank — issuing cards directly to consumers and processing transactions for merchants.

The real-time process of checking whether a transaction should be approved. Happens in ~2 seconds. No money moves — it's just a promise.

The rails that route transactions between issuers, acquirers, and merchants. Visa, Mastercard, American Express, and Discover are the major global networks.

The process of exchanging transaction details between acquirer and issuer at the end of the day. Like submitting the paperwork.

A payment system where one company handles everything — issuing cards, routing transactions, and settling with merchants (Amex, Discover). 'Closed' because it's all in-house.

The fee the merchant's bank pays the cardholder's bank for each transaction. Set by the card network, not negotiable by the merchant. Typically 1.5–2.5%.

The bank that gave you your credit card. They're the ones who approve transactions, extend credit, and send you monthly statements.

Like Visa, Mastercard is a network, not a bank. They don't issue cards — your bank does that. Mastercard provides the rails, the rules, and the brand.

The total fee a merchant pays to accept a card transaction. Called a 'discount' because the merchant receives less than the full amount — typically 1.5% to 3.5%.

A payment system where any bank can issue cards on the network (Visa, Mastercard). 'Open' because many parties participate — issuers, acquirers, network, merchants, cardholders.

When money actually changes hands. The issuer sends funds to the acquirer (minus interchange fees), who deposits them in the merchant's account (minus processing fees).

Visa doesn't issue cards or extend credit. They operate the network — the VisaNet system processes over 65,000 transactions per second and connects 14,000+ financial institutions worldwide.