Zero-amount authorization
A card authorisation for nothing at all, checking that a card exists and works without holding any funds.
Merchants use it when they want to store a card without charging it yet: free trials, subscriptions that start next month, or a hotel that wants a guarantee. The issuer checks the card number, expiry, CVV and often the address via AVS, and replies with an ordinary approval or decline code. No balance moves. Visa calls the message Account Verification.
The old trick was to charge a dollar and then reverse it. Customers saw a mystery charge, and reversals that never arrived left holds on accounts for days. The card networks have therefore pushed merchants onto zero amounts. Card testers appreciate the change too, since a stolen card can be checked without its owner seeing any charge whatsoever.