The statement balance is the total amount owed on a credit card at the end of a billing cycle — the amount shown on your monthly statement. Paying the full statement balance by the due date avoids all interest charges on those purchases.
Credit card billing cycles typically run 28–31 days. On the last day of the cycle (the 'closing date'), the issuer locks in your statement balance — the sum of all purchases, fees, interest charges, and any previous unpaid balance minus payments made during the cycle. Paying the full statement balance by the due date (typically 21–25 days after the closing date, per the CFPB's minimum [[grace-period]] rule under the CARD Act) means no interest accrues on those purchases. Paying only the [[minimum-payment]] leaves the remainder subject to interest — often at APRs of 20–29% — compounding daily. Note the difference between statement balance and current balance: the current balance includes transactions made after the cycle closed that haven't appeared on a statement yet. You must pay the statement balance to avoid interest; paying the current balance also satisfies that requirement.
Statement balance is fixed at cycle end. Current balance reflects all charges through today — including post-cycle purchases. Paying the statement balance by the due date avoids interest; you don't have to pay the current balance to achieve that.
Yes. Interest accrues on the unpaid portion of the statement balance. Only paying the full statement balance (or more) avoids interest on those purchases.