The famous $1 status check: the pump pre-authorizes a token amount (or ~$100–175 hold), then completes for the real total later. The reason for those mystery holds on your statement.
The MCC quietly sets the interchange rate, whether the purchase earns rewards, whether it's treated as a cash advance, and how risk models see the merchant. Acquirers assign it at onboarding — and miscoding is a compliance problem, not a shortcut.
Merchant Category Codes are defined under ISO 18245, with network-specific usage on top. Around 500 exist; the ones that come up in real conversations are in our lookup tool.