+Card numbers are unique sequences of digits that identify a specific [Payment Card](/wiki/Payment_Card). They enable secure [Transaction](/wiki/Transaction)s, linking to an associated financial account. These numerical identifiers are fundamental to modern commerce and digital security.
+## See also
+- [Credit Card](/wiki/Credit_Card)
+- [Debit Card](/wiki/Debit_Card)
+- [Payment System](/wiki/Payment_System)
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