Many things bad credit credit cards
That means that each month, you are charged that month's portion of the interest rate (for a 12% interest rate, you are charged 1% per month), and that money is added to the amount that is charged interest. You end up paying interest on your interest. If you cannot pay off your credit card for several years, as is likely when people run up bills in the thousands of dollars, you will end up paying more in interest than the original item cost. Don't let that happen. Pay off new charges as quickly as you can.