Annual Fee – Your annual fee for this credit card

Current Balance – Current outstanding balance on your credit card

Interest Rate (APR) – The annual percentage rate for this credit card

Minimum Payment – The amount you must pay this month on this credit card (You may pay more, but you may not pay less than this amount.)

Principal – The formal definition is "a sum placed at interest, due as a debt." For your purposes, look at it as the amount left that you actually charged—and still must pay back.

Keep in mind that when you make a partial payment on the amount that you owe, some of the money is used to pay the interest charges. That means that only part of your payment is used to pay the principal.