Authorization request
Merchant sends card + amount to acquirer. Acquirer routes to network (Visa/MC). Network routes to issuing bank.
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Authorization request
Merchant sends card + amount to acquirer. Acquirer routes to network (Visa/MC). Network routes to issuing bank.
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Issuer decision
Bank checks: valid card? sufficient credit? fraud rules? Returns approve/decline in ~500ms.
3D Secure challenge
Optional: high-risk transactions may trigger challenge. Issuer verifies cardholder via app/OTP. Adds ~10s but shifts fraud liability.
Capture is separate
Auth reserves funds. Capture (usually next day) actually moves money. Merchant can void auth or capture partial amount.
Settlement + fees
Interchange fee (~2%) split between issuer, network, acquirer. Merchant nets ~97% of transaction. Chargebacks handled through similar reverse flow.