Passing a store, you might just step in and see if the store has received any new CDs. Once in the store, you're delighted to discover some new CDs that you must have. You could buy them later, of course, but you're already here, so why not now? In the checkout line you wonder whether to write a check or pay with a credit card. Either way would be OK, you suppose. The trouble with writing a check, though, is that you don't have much money left in your checking account. Using the credit card you won't have to pay at once, and when you do pay, you will only have to pay a little a month. So you hand the salesperson your plastic card, and that's the deal!     There are a few good things about credit cards. For one thing, it's almost impossible to rent a car without a credit card. For another, they are helpful if you are in a situation where you don't have your checkbook or you have little cash with you. What are the disadvantages? One is that few people have the discipline to use their credit cards wisely. Instead, many fall into the buy-now-pay-later trap. Many become "addicted to plastic." Another disadvantage is that credit cards are more abstract than money or checks and thus contribute to our having less control over our money. Bank notes are physical things, and you have to  _ your checking account every month when you pay with a check. This takes a bit of work, and although it's painful, it's more realistic. Credit cards represent the abstract, lending a certain air of unreality to the stage of managing your finances. All you do is sign your name; someone else does the math for you. What is the disadvantage of the credit cards?
They will leave you buying more than what you can really afford. They will leave you spending more than paying in cash or with checks. They can save you some money sometimes but later cost more. They can save you some money but increase interest in your bank account.