Credits cards are a convenience, not a crutch. Credit cards are a great way to make purchases and record to the penny your spending. They also provide a way to postpone payment on items and thereby earn more interest on your money. For example, if you have a money market account that gives you 5% annual interest and you spend $1000 a month through your credit card, you can keep that $1000 in your money market account for an additional month. At the end of a year you would have earned an addit.