A credit card user is issued a credit card after they have been approved by a provider up to a pre-negotiated credit limit. The owner of the credit card is now able to make purchases from merchants who support that credit card. When a purchase is made, the credit card user indicates their consent to pay, usually by signing a receipt with a record of the card details and indicating the amount to be paid. More recently, electronic verification systems have allowed merchants (using a strip of magnetized material on the card holding information in a similar manner to magnetic tape or a floppy disk) to verify that the card is valid and the credit card customer has sufficient credit to cover the purchase in a few seconds, allowing the verification to happen at time of purchase. Some services can be paid for over the telephone by credit card merely by quoting the number embossed onto the card (the credit card number), and they can be used in a similar manner to pay for purchases from online vendors.

Each month, the credit card user is sent a statement indicating the purchases undertaken with the card, and the total amount owing. The cardholder must then pay a minimum proportion of the bill by a due date, and may choose to pay more or indeed pay the entire amount owing. The credit provider charges interest on the amount owing (typically, a fairly high rate much higher than most other forms of debt). Typically, credit card issuers will waive interest charges if the balance is paid in full each month, which allows the credit card to serve as a form of revolving credit.

Secured Credit Cards
A secured credit card is a special type of credit card in which you must first put down a deposit between 50% and 100% of the total amount of credit you desire. Thus if you put down $500, you will be given credit in the range of $250-$500. This deposit is held in a special savings account. The owner of the secured credit card is still expected to make regular payment, as he or she would with a regular credit card, but should he or she default on a payment, the card issuer can deduct the payment out of the deposit. Secure credit cards are an advantage to anyone with poor or no credit history. They are often offered to people as a means of rebuilding one’s credit. Secured credit cards are available with both Visa and MasterCard logos on them.

Features of Credit Cards
As well as convenient, accessible credit, the cards offered consumers an easy way to track expenses, which is necessary both for monitoring personal expenditure and the tracking of work-related expenses for taxation and reimbursement purposes. They have now spread worldwide, and are offered in a huge variety of permutations with differing credit limits, repayment arrangements (some cards offer interest-free periods, while others do not but compensate with much lower interest rates), and other perks (such as rewards schemes in which points "earned" for purchasing goods with the card can be reclaimed for further goods and services).

In addition, some countries such as the United States limit the amount that a consumer can be held liable for fraudulent transactions which shifts the liability to the merchant. This encourages the use of credit cards for electronic and mail order transactions, collectively called "card not present" transactions. They have spread far and wide beyond their initial market of the wealthy businessman and are now ubiquitous amongst the middle class of most Western countries.

Security of Credit Cards
The relatively low security of the credit card system presents many opportunities for fraud. However, this does not imply that the system is broken. The goal of the credit card companies is not to eliminate fraud, but to reduce it to manageable levels, such that the total cost of both fraud and fraud prevention is minimized. This implies that high-cost low-return fraud prevention measures will not be used if their cost exceeds the potential gains from fraud reduction. This opportunity for fraud has created a black market in stolen credit card numbers, which must generally be used quickly before the cards are reported stolen.

Three improvements to card security are being introduced to the more common credit card networks at the time of writing. An additional 3-4 digit code is now present on the back of most cards, for use in "card not present" transactions. The on-line verification system used by merchants is being enhanced to require a 4 digit Personal Identification Number (PIN) known only to the card holder, and the cards themselves are being replaced with similar-looking tamper-resistant smart cards which are intended to make forgery more difficult. The majority of smartcard (IC card) based credit cards comply with the EMV (Europay Visa MasterCard) standard.

The 3-4 digit numbers for use in "card not present" transactions are to be found in different places on the various cards, and are referred to differently by the card issuers.