For credit cards, the grace period is the amount of time you have to pay your balance in full without paying a finance charge. The grace period usually starts on the billing date and ends a certain number of days after. Grace periods are typically between 21 and 25 days. Longer grace periods are better because they give you more time to pay off your credit card balance and avoid interest charges.
Certain types of balances may not have a grace period. For example, cash advances and balance transfers don't typically have a grace period and begin accruing interest as soon as the transaction posts to your account. Additionally, new purchases may not have a grace period if you already have a balance on your credit card when the purchase is made.
So you can take full advantage of your grace period, credit card issuers will be required to mail your billing statement at least 21 days before finance charges would be assessed. This new law goes into effect on February 22, 2010.
Loans also have a grace period which is the period of time following payment due date that the loan will not default or be cancelled even though payment is due. You can make your after the due date, but during the grace period to avoid late payment penalties.