If you use a debit card to check into a hotel for five nights, it will notify your bank how much it expects you to spend. The same thing happens when you rent a car.

Your bank will put a "block" on your checking or prepaid debit card account for however much those bills are expected to be.

That amount is now unavailable to pay other debit card purchases or checks. The block remains in place until you check out, or return the car, and the hotel or rental company notifies your bank of the actual amount.

Hotels and rental car companies make a bad situation worse by adding potential charges for food, phone charges or gasoline to what they report to your bank. As a result, the blocked amount is almost always more than the bill turns out to be.

If the block exceeds the amount in your checking account, you're considered to be overdrawn and start racking up overdraft fees for any checks or debit purchases the bank must pay. It doesn't matter if you make a deposit during your trip that more than covers all of your expenses before you check out or return the car.

Our smart owner's guide to debit cards can help you enjoy the benefits without a lot of nasty fees and other problems.