Transaction flow is the sequence of steps that moves a purchase from checkout to payment processing and final authorization. It usually includes cart review, customer authentication, order submission, payment gateway handoff, fraud checks, issuer approval, and confirmation back to the merchant.
In cyber security, transaction flow matters because each handoff is a place where attackers can intercept, alter, or abuse data. Fraudsters may automate card testing, manipulate payment fields, replay requests, or exploit weak validation between systems. Defenders protect the flow with encryption, strong session controls, device and behavior checks, duplicate-transaction detection, and layered fraud scoring. Mapping the full flow helps teams see where trust changes, where sensitive data moves, and where controls should be enforced to stop fraud without breaking legitimate purchases.