Glossary
Issuer processing
The real-time engine that authorises, clears and settles card transactions on the issuing side - the system that says yes or no to every payment.
When a card is tapped, the scheme routes the authorisation to the issuer's processor, which checks balance, limits and fraud signals and answers in milliseconds. Modern issuer processors expose this pipeline via APIs and webhooks so programmes can build custom logic.
The processor sees the entire transaction stream - which is why processor jurisdiction and hosting matter as much as the licence. A European processor with EEA hosting keeps that data under GDPR even though the scheme is American.