Many credit cards will offer an introductory rate for signing up for a new visa or mastercard. Almost invariably, this means that the standard rate that you will receive after the introductory period is over will be much higher and less attractive.
If you purchase items on the card with this low rate, you will soon be paying much more for them than you anticipate. As a general rule, you should read the fine print; and, if the interest rate you will be receiving after the introductory period is not attractive, don't take the card!
Many people will be tempted to sign up for the card under the premise that they will only be using it during the introductory period, or that they will roll over balances temporarily. Unfortunately, most of us have good intentions which are not followed by the actions we had hoped for.
Best advice, get the lowest rate you can get, ove ...