Credit Card Fraud Detection Using K Means

A credit card is a small plastic card issued to users as a system of payment. It allows its holder to buy goods and services based on the holder's promise to pay for these goods and services. The issuer of the card creates a revolving account and grants a line of credit to the consumer (or the user) from which the user can borrow money for payment to a merchant or as a cash advance to the user.

A credit card is different from a charge card: a charge card requires the balance to be paid in full each month. In contrast, credit cards allow the consumers a continuing balance of debt, subject to interest being charged. A credit card also differs from a cash card, which can be used like currency by the owner of the card. Most credit cards are issued by banks or credit unions, and are the shape and size specified by the ISO/IEC 7810 standard as ID1. This is defined as 85.60 *53.98 mm (33/8 * 21/8 in) in size.

Credit cards are issued by a credit card issuer, such as a bank or credit union, after an account has been approved by the credit provider, after which cardholders can use it to make purchases at merchants accepting that card. Merchants often advertise which cards they accept by displaying acceptance marks generally derived from logos or may communicate this orally, as in "We take (brands X, Y, and Z)" or "We don't take credit cards". When a purchase is made, the credit card user agrees to pay the card issuer. The cardholder indicates consent to pay by signing a receipt with a record of the card details and indicating the amount to be paid or by entering a personal identification number (PIN).

Also, many merchants now accept verbal authorizations via telephone and electronic authorization using the Internet, known as a card not present transaction (CNP). Electronic verification systems allow merchants to verify in a few seconds that the card is valid and the credit card customer has sufficient credit to cover the purchase, allowing the verification to happen at time of purchase. The verification is performed using a credit card payment terminal or point-of-sale (POS) system with a communications link to the merchant's acquiring bank. Data from the card is obtained from a magnetic stripe or chip on the card; the latter system is called Chip and PIN in the United Kingdom and Ireland, and is implemented as an EMV card.

For card not present transactions where the card is not shown (e.g., e-commerce, mail order, and telephone sales), merchants additionally verify that the customer is in physical possession of the card and is the authorized user by asking for additional information such as the security code printed on the back of the card, date of expiry, and billing address.

Each month, the credit card user is sent a statement indicating the purchases undertaken with the card, any outstanding fees, and the total amount owed. After receiving the statement, the cardholder may dispute any charges that he or she thinks are incorrect , which limits cardholder liability for unauthorized use of a credit card to $50, and the Fair Credit Billing Act for details of the US regulations). Otherwise, the cardholder must pay a defined minimum proportion of the bill by a due date, or may choose to pay a higher amount up to the entire amount owed. The credit issuer charges interest on the amount owed if the balance is not paid in full .

In addition, if the credit card user fails to make at least the minimum payment by the due date, the issuer may impose a "late fee" and/or other penalties on the user. To help mitigate this, some financial institutions can arrange for automatic payments to be deducted from the user's bank accounts, thus avoiding such penalties altogether as long as the cardholder has sufficient funds.

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