Credit Card Interest Ratesby Amy Fontinelle
To add insult to injury, that great annual percentage rate (APR) you thought you had on your credit card might have merely been an introductory rate that was subject to increase after a certain period if the balance has not been paid in full. An 8.99% APR can skyrocket to a 29.99% APR in the blink of an eye. "But that will never happen to me," you might say."I'll pay my balance in full as soon as it's payday." You may have the best of intentions, but they can easily get derailed by an unplanned expense like a car repair or an unexpected event like losing your job.
Source: http://www.investopedia.com/articles/pf/08/recession-proof-your-life.asp; http://www.twopenniesearned.blogspot.com/