Credit card © Hill Street Studios, Getty Images

Credit cards may appear to be convenient plastic rectangles in your wallet, but they can be something more sinister: sneaky debt traps.

The booby traps you encounter may not be your fault but rather those of an industry that values profits and thrives off of your mistakes.

But no need to read the fine print on your credit card terms or do the heavy lifting: below are some secrets about credit cards that are buried in all those numbers and regulations you don't get paid enough to research.

1. Paying minimum payments drags balances out

The minimum payment on your bills isn't a dare; it's what's been mathematically calculated to drag your payment out so long that you pay at least double what you actually owe. This isn't just credit cards; it applies to every consumer loan in the world. The only difference between banks and loan sharks is the amount of time you're given before the compound interest on your loan compels them to come pounding on your door.

"The higher your interest rate, the more your payment goes toward interest, rather than toward principal, and the longer it takes to get out of debt,'" says Gerri Detweiler, director of consumer education at Credit.com, an independent website that helps consumers make smarter credit decisions.

Credit.com includes a free credit card payoff calculator (which you can access here) that allows you to input your credit card's balance, interest rate and minimum payments to see the sobering truth about how long it'll take to pay off your balance, along with how much interest you'll pay by the end.

And remember, we're discussing only on your credit card debt (which is only a small portion of your overall debt). Let's not forget the 2014 Student Loan Outlook...also how New Mortgage Rules Go Back to the Future.

2. Late payments aren't regulated very well

The laws about late payments are sketchy at best. They're capped at $25 for your first infraction, but the government only protects you from the banks until you really start getting into financial troubles.

If you're habitually late, not only will you be paying the banks all that interest above, but you'll also be paying higher and higher late fees. We saw this in the mortgage industry as well, when struggling borrowers were hit with exorbitant force-placed insurance fees, pushing them over the foreclosure cliff. We live in a capitalistic society, and if you don't pay your bills, Uncle Sam will turn his back on you.

"Timely payments establish a track record of reliability and boost credit," says Randy Hopper, AVP of credit card lending at Navy Federal Credit Union. "If possible, set up automatic monthly payments along with text and email alerts to remind you of your due date."

3. Interest rates aren't capped

There are a lot of laws regarding credit card interest rates, but they have more to do with the way banks were selling the cards to you. What they do is give you a low introductory rate, then hike the interest rate up as high and as often as they can. The CARD Act President Barack Obama signed in 2009 somewhat limits this deceptive marketing technique, but where there's money to be made, banks will find a way.

"If you have a variable interest rate, call your credit card company and ask that the rate be capped or ask to switch to a fixed interest rate," says Harrine Freeman, author of How to Get Out of Debt: Get an "A" Credit Rating for Free (Adept, 2006). You can pester the credit card company enough to lower your rate if you're vigilant, but normally the powers that be just keep upping your available credit while slowly creeping that rate up on you and extending the term limits.

If you're confounded and interested in compound interest, then check out what BankingMyWay taught MainStreet on the subject in How to Avoid the Credit Card Interest Trap.

4. Making 2 payments per month lowers interest

Interest is compounded in various ways, but you're not interested in any of them. The very least you need to know about credit card interest is it is a revolving line of credit. There's no penalty for paying credit cards off early (although there are subtle penalties for paying them in full every month).

Making two payments each month to your credit card drastically reduces the interest you'll pay on it. Even if you can't make two full payments, splitting your normal monthly payment in half and paying it in two installments makes a bigger difference in the long run than you think. It's like a butterfly flapping its wings in your present to create a tsunami of cash flow in your future.

5. Any late payment raises rates across the board

Real life is exactly like high school, and your credit report is your permanent record; keep that in mind when debt collectors call you. In the school of life, your financial administration tracks tardies. You'll get perfect attendance awards so long as you show up on time. If you're tardy in one class, your teachers start talking, and you're labeled as a problem child. Keep in mind, though, not everyone reports to the credit bureaus; the only way you'll know is by requesting a copy of your permanent records.

6. Cash advances are paid off last

If you need money to pay off a bill that doesn't accept credit, you're better off maxing out your credit card buying things you can turn around and sell than you are pulling cash out of your credit card. The banks rearrange balances so the highest interest balances are paid off last. Take a look at your subsidized and unsubsidized student loan balances if you want to see this ridiculousness in action.

Your credit card may have a 2% rate, but the interest rate on cash advances (the highest interest rate transaction) is at least triple that. This means the only way you'll ever stop paying that high interest rate is by paying off your entire credit card balance, which brings us to the next topic.

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