Card-on-file is the shorthand for the stored card behind every card-on-file transaction, the main entry, and means card details that a merchant or payment provider keeps, with the cardholder's agreement, so that it can charge the card again without the customer re-entering them.
Stored cards power one-click checkout, ride-hailing and food delivery apps, subscriptions, instalment plans and account top-ups. Card scheme rules call the stored data a stored credential and require merchants to obtain consent, disclose how the card will be used, and flag the first and later transactions correctly in authorisation messages. Later charges may be started by the customer, such as a repeat purchase, or by the merchant, such as a monthly bill, known as a merchant-initiated transaction.
"Card-on-file" is used both as an adjective and as a noun for the stored card itself, while the main entry focuses on the transactions. To reduce security risk, most merchants store a token rather than the card number, often a network token that stays valid when the card is replaced. Card updater services also keep stored details current, covered under card account updater.