A message to the woman in front of me at the grocery store this weekend: I didn't mind your whining child. In fact, I thought your baby was kind of cute. And I didn't mind your huge load of groceries; I thought it would be the fastest line (I was wrong). And I applaud your use of coupons -- something that requires planning that typically escapes me.

But my nerves snapped when you pulled out your checkbook and laboriously wrote out the check for your purchase, which caused the sales clerk to call a supervisor for approval, who required a look at your driver's license before finding a pen to put her initials on the check. And I also resent the fact that, instead of moving along, you decided to responsibly subtract that check from the balance in your check register.

My mind screamed: "Use a debit card instead of a check!"

I wanted to approach you -- as I have approached others several times -- and ask why on Earth you don't move into the 21st century and use your debit card. It would take one swipe in the handy machine and a second or two to insert your personal identification number, leaving you with nothing to sign or subtract.

Of course you have a debit card. You use it to get cash! But it's not just for ATMs. In fact, two-thirds of Visa's transactions now come from debit cards.

Why keep all of us waiting, when your ATM card with the Visa or Mastercard logo is an instant debit card that you could easily use at the supermarket, or dozens of other places? You'd never incur any finance charges. You could view your checking account balance instantly at your bank -- or any ATM. And at your bank's website you could securely track exactly where you spent all your money -- at the grocery store, dry cleaner, gas station or, even for that grande latte, at Starbucks.

Everyone in line behind you at every one of those stores would bless you for using this responsible, modern convenience. Merchants would love you. They pay significantly less in processing when you use debit than when you use a credit card.

Your debit card is safer than cash, because you're 100% protected against fraud if you lose your card and money is taken out of your account. Yes, credit cards provide an additional level of protection, but you're unlikely to dispute your purchase at the grocery store with the merchant.

Using a debit card is so much faster than writing a check. Plus, admit it: You can't subtract!

Yes, if you're collecting miles or rewards points, a traditional credit card may be a better deal. But if you don't pay off that credit card in full each month, you're paying interest on the balance. What good is it to use coupons in the grocery store to save pennies if you're losing dollars in interest on your credit card?

Save the credit card for large purchases or for purchases that require you to stretch out payments over a couple of months. Or for purchases where you need the protection of the card issuer in case of a dispute.

Are you trying to track your spending? So use that debit card instead of cash. Every time you go online to see your balance, you'll be able to see exactly where you used that debit card and how much you spent. If you use Quicken or MicrosoftMoney, you can download that information into these helpful programs that will display your spending in categories -- a bar chart or a pie-shaped chart.

That's far better than withdrawing cash at the ATM and wondering where it all went!

I respect the fact that you were being conservative, careful and concerned about money when you used a personal check. But get that checkbook out of your purse. It takes up space. It's a dangerous key to your finances, and your entire identity, if your purse is stolen.

Using digits instead of paper checks is environmentally responsible. Your debit card will save millions of trees that would otherwise be made into paper checks -- and millions of gallons of gas that would be used to transport those checks from merchant to bank to clearing center and back to your bank.

As Dustin Hoffman learned in The Graduate decades ago: Plastic is the way of the future! And the future is now. You know that. I watched the bagboy ask you the usual question: Paper or plastic? You chose plastic for your grocery bags. Good move. Now think of all the energy -- emotional and otherwise -- you'd save yourself, and those in line behind you, if you would only choose plastic at the checkout line.

And that's the Savage Truth.

Terry Savage is an expert on personal finance and also appears as a commentator on national television on issues related to investing and the financial markets. Savage?s personal finance column in the Chicago Sun-Times is nationally syndicated, and she released her fourth book, The Savage Number: How Much Money Do You Need? in June 2005. Savage was the first woman trader on the Chicago Board Options Exchange and is a registered investment adviser for stocks and futures. A Phi Beta Kappa graduate of the University of Michigan, Savage currently serves as a director of the Chicago Mercantile Exchange Corp. She also has served on the boards of McDonald?s and Pennzoil.

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