Is credit card debt really such a big problem in America? Unfortunately, it is. Americans owe three-quarters of a trillion dollars in credit card debt. The average American household with credit cards owes about $9,000, according to Worse, the average U.S. household with cards pays about $1,100 in credit card interest alone per year.

Once you've fallen prey to the easy-money attraction of credit cards, it's very hard to dig yourself out. It can be tempting to simply ignore your balance and pay the minimum requirement on your card. This is a dangerous approach, though. Let's consider an example.

Morris owes $5,000 on his Zirconium MegaCharge card, which extracts 16% in interest each year. If he manages to scrape together enough money to pay it all off in a year, he'll be forking over about $450 per month and will pay more than $400 in interest. In contrast, if he takes his time paying it off and does so over 10 years, he'll pay roughly $84 per month and will end up paying a whopping $5,080 in interest. This means he will have paid more in interest than he originally borrowed!

Building up credit card debt is kind of like investing -- in reverse. With investing, your money grows. Mired in plastic, it shrinks. Think back to Morris and that $84 per month he paid on his debt for 10 years. If he'd been parking it regularly in the stock market and earning its historical annual average of about 10%, he'd end up with more than $15,000 after 10 years. (And, if he'd invested it in the stock of a company like Wal-Mart (NYSE:WMT) or eBay (NASDAQ:EBAY) years ago, he might have more than $30,000 or $40,000.)

Aim to pay off all your credit card charges in full each month. If you're in too deep to do that, try renegotiating your interest rate. If you have a sound credit history and explain that you'll be moving your debt elsewhere if your rate isn't lowered, the credit card company may knock it down a few percentage points. That can make a big difference.

Credit cards may be convenient, but they can devour your financial future. Use them carefully.

If you or someone you care about is mired in credit card debt, learn more in our Get Out of Debt area and in this special feature on credit card debt.

If you've got your personal finances under control and would like to make the most of money you'll be needing in the next few years, visit our Savings Center, where we offer you some good deals on interest rates. We even offer a special Motley Fool Visa card that's worth checking out.