How payments actually work
Step-by-step explainers on the rails, cryptography, and standards behind modern digital payments - written for operators, engineers, and curious readers.
How Card Payments Work
The four-party model, authorization vs. settlement, interchange economics, and the data flow behind every swipe, dip, or tap.
How Contactless Payments Work
The radio standard, cryptographic primitives, and CVM logic behind contactless tap-to-pay.
How Payment Tokenization Works
Network tokens vs. acquirer tokens, the TR-31 derivation, and why tokenization shrinks PCI scope.
How FedNow Works
The technical model, ISO 20022 messaging, and the role of FedNow in the U.S. instant payments duopoly.
How Pix Works
Pix Keys, the DICT directory, the QR code formats, and the regulatory choices that drove rapid adoption.
How PCI DSS Works
Merchant levels, SAQ types, scope reduction via tokenization, and the v4.0 customized approach.