That's the rate the issuer applies to your outstanding balance to figure the finance charge for each billing period. This is the time between the date of a purchase and the date interest starts being charged on that purchase. If your card has a standard grace period you have an opportunity to avoid finance charges by paying your current balance in full. Some issuers allow a grace period for new purchases even if you do not pay your balance in full every month. If there is no grace period, the issuer imposes a finance charge from the date you use your card or from the date each transaction is posted to your account.
Some issuers charge no annual fee.
Some issuers charge a fee if you use the card to get a cash advance, if you fail to make a payment on time, or if you exceed your credit limit. Some may charge a flat fee every month whether you use the card or not. Once you get a card, sign it immediately so no one else can use it. Note that the accompanying papers have important information, such as customer service telephone numbers, in case your card is lost or stolen. File this information in a safe place.