Credit cards touch all five factors that make up your FICO score — and they’re the fastest-moving lever most consumers have. How you use them (or misuse them) shapes your score more than almost any other financial product in your wallet.

A credit card grace period is the window between the close of your billing cycle and your payment due date — typically 21 to 25 days. Pay your full statement balance before the due date, and you owe zero interest on purchases.

A credit card limit is the maximum balance your issuer will allow on your account at any given time. It’s set when you open the account based on your credit score, income, existing debt, and the issuer’s risk model — and it directly controls your credit utilization ratio, the second-largest factor in your FICO score.

An authorized user is someone added to another person’s credit card account who can make purchases but bears no legal responsibility for the debt. A joint account holder is a co-owner of the account who shares equal liability for the balance and equal rights to use the card.

A hard inquiry is a formal credit check triggered when you apply for new credit — such as a credit card, loan, or mortgage — that is recorded on your credit report and can temporarily lower your score. A soft inquiry is an informal credit check for background screening, prequalification, or account reviews that does not affect your score and is not visible to other lenders.

Credit card fees are charges your issuer adds to your account for specific actions or account features — separate from interest — including annual fees, late fees, foreign transaction fees, balance transfer fees, cash advance fees, and returned payment fees.

Credit utilization ratio is the percentage of your total available revolving credit that you’re currently using, calculated by dividing your total credit card balances by your total credit limits.

Credit card interest is the cost your issuer charges for carrying an unpaid balance, calculated by converting your annual percentage rate into a daily rate and applying it to your average balance across the billing cycle.

A minimum credit card payment is the smallest amount you must pay each billing cycle to keep your account in good standing — typically the greater of a set percentage of your outstanding balance or a flat dollar floor established by your issuer.

A credit card is a revolving line of credit issued by a bank that lets you borrow money from a card network (like Visa or Mastercard) to pay merchants, with the balance due at the end of your billing cycle.