Card number validation typically involves several steps:
Checksum Validation: This is usually done using the Luhn algorithm, which checks if the card number entered is mathematically valid. Card Type Identification: Different card issuers (like Visa, MasterCard, etc.) have specific number ranges. Validation software often checks these ranges to identify the card type. Length Check: Valid card numbers have a specific length. For instance, Visa cards typically have 16 digits.