As a responsible credit card user, you should understand the terms used by your issuing bank.  Among those you're likely to find are the following:

Miscellaneous Fees
Some card issuers require an annual fee - the amount you must pay to get a card or to renew it every year.  Some banks also charge fees for submitting an application, for being late with a payment, for taking out a cash advance, for exceeding your credit limit, or for maintaining a zero balance.  Read your statement carefully so that you know all of the terms and conditions.

Grace Period
This is the number of days the bank allows you to borrow their money interest-free.  Grace periods vary, usually from two weeks to 25 days, depending on the bank that issues the credit card.

This period is usually applied to new purchases, but only if there is no old balance being carried forward.  After the grace period expires, if you haven't paid your balances in full, interest can be accrued from the date of purchase.

Some cards do not offer interest-free grace periods, and you start incurring interest from the date of any purchase.

Cash Advances
The issuing bank or financial institutions treats cash advances like loans, not like purchases or merchandise.  When you take a cash advance, interest begins to accrue differently - sometimes without a grace period and at a higher rate.
Check with your card-issuer for cash advance fees and interests.

Interest Calculation
When you use your credit card, the issuing bank or financial institution is really giving you a loan for the amount of your purchases.  The bank charges a fee - called interest - for using its money.  The credit card company pays the travel agent or the furniture store within a few days of the transaction, and you must begin repaying the loan when your monthly statement arrives in the mail.

All interest charges can usually be avoided by paying the balance in full within the time limit specified on your statement.  Check the fine print though, because some banks charge a fee for maintaining a "$0 balance" or don't have a "grace period".

If you choose not to pay all you've borrowed from the bank - banks call that "revolving the balance" - interest will be charged.  Obviously, the quicker the balance is paid in full, the less interest is paid.
Be sure to learn about the terms and policies of your credit card.  Interest rates will vary by card, some may begin charging immediately without any "grace period".  Some start charging interest from the date of transaction or the date when the transaction is processed in the system.  Others may start charging interest from the date on your statement.

Banks use various methods to calculate interest, and it's up to you to learn how your bank computes these charges.  Unlike a house mortgage or a car loan, credit card interest can be charged by the day or by the month.

If you do not pay the balance in full, interest on the unpaid amount, or revolving balance, will be added to the total amount owed.  When this happens, you are paying interest on interest, also called compound interest.  Any new purchases you make can be included in the total balance immediately and will begin to accrue interest from the date of purchase.  If you have a large balance, paying only the minimum amount each month can be an expensive way to use your credit card.

Try to anticipate your credit needs.  A few months before the holidays or before you head off on that dream vacation, start paying down your balance by sending in more than the minimum payment.
When you begin charging holiday gifts or charging for your vacation, you won't be piling new bills on top of old ones, and there will be less chance of exceeding your credit limit.

Be sure to know what your APR (annual percentage rate or interest rate) is, and always include the cost of credit in your budgeting or money management.

Foreign Currency Transactions
Before you travel overseas and use your card to make purchases in foreign currency, get to know the conversion charges involved.

The conversion from a foreign currency to your local currency is a service that card associations such as Visa provide to their member financial institutions daily at wholesale market rates plus an additional assessment, in Visa's case, an assessment of one percent.

Your card-issuing bank decides whether to absorb or pass on its currency conversion costs to you, and it may or may not mark up the rate it receives from the card associations.

Card issuers decide what currency conversion rates to charge you, and they do charge different rates, so you can consult your card-issuing financial institution for its policy on setting fees and shop around for the card offering that best suits your needs.

The exchange rate of a particular currency will depend upon the date a merchant submits the transaction to the bank for posting to your account. This may or may not be the same day as the retail transaction occurred. At the time of the purchase, the cardholder's bank, merchant and/or the card associations do not know the exact exchange rate that will apply because it will not be set until the transaction is submitted for processing.