A grace period is the time between the end of a billing cycle and the date you need to make your payment.
During this period, you will not be charged any interest fees as long as you pay your balance in full by the due date.
Credit card companies are not required to give a grace period but they do give a grace period on purchases.
If you are not carrying a balance during the grace period, you don't have to pay interest when you pay the balance in full.
If you lose your grace period by not paying your balance in full, you will be charged interest on the unpaid balance.
You will also be charged interest on purchases in the new billing cycle starting on the day new purchases are made.
Credit card companies must send their bills to you at least 21 days before the balance payment is due.
With credit cards, grace period applies only to purchase transactions. In case of a cash advance or check, it doesn't.
Bonus tip: To keep your grace period, ensure you pay your bill on time and in full each month without fail.