Credit cards are one of the fastest ways to get into financial ruin in college. With interest rates frequently exceeding 20 percent and the temptation to spend everywhere, debt can pile up quickly.

Often it does. The average undergraduate has $2,200 in credit card debt; the average graduate student has $5,500. And statistics suggest that students are increasingly getting themselves into more debt. Credit card debt among college students has doubled in the past decade, and the number of college-aged Americans declaring bankruptcy doubled in the 1990s.

Nonetheless, all students should get a credit card – or two or three.

Why play with fire? Your credit score.

Credit scores are a little-understood and increasingly important beast. They determine whether you can get a mortgage to buy a house, and the interest rate you will pay. They determine if you can rent a house, and employers look at them to see how good you are at managing yourself. And increasingly they are used to determine rates on everything from car insurance to life insurance, a trend that should accelerate.

Scores range from 300 to 850 and are determined by a quasi-secret formula maintained by the Fair Isaac Corporation. The score is an attempt to quantify how likely you are to pay off debts, taking into account factors such as punctuality of payments, amount of available credit used and length of credit history.

To make matters more confusing, each person has not one but three credit reports/scores. Three corporations, Equifax, Experian and TransUnion, each maintain your credit report independently. While the reports may vary, they should be very similar in general.

However, you don’t start building credit until you begin to establish a credit history, hence the need to get a credit card and use it wisely. The advice is not to build up credit card debt. It is simply to have a credit card with little to no balance to build credit. Ideally, that would mean using it for a few purchases per month and immediately paying off the balance to avoid heinous interest charges.

The goal is to get to the elusive score of 725, putting students in the top half of credit scores and in the “”good credit”” category. Any score below 660 is not good.

A score of 725 means you will be able to get the lowest rate when it matters most, on your home loan. But aside from the credit score, the quality of credit matters. Lenders want to see more than just one card on the report, even if it is paid on time. Therefore, students should get more than one credit card and try to get additional items on their credit report. Again, this doesn’t mean to go into debt, which can ruin a credit report. And if you do need to borrow, the best place besides family is student debt, which carries a much lower interest rate than credit cards.

Students who first seek out a credit card may be surprised to find out there’s a catch-22 with getting one. Until you have credit, people don’t want to give you credit, but you can’t build credit until someone will give you credit. Good places to get the first card are department stores and retail outlets such as American Eagle Outfitters, which tend to have looser requirements than most credit cards.

One very helpful tip: If you have helpful and trusting parents, have them put you on their credit card as an “”authorized user.”” Even if they don’t give you a copy of the actual card, and even if you yourself don’t make any purchases, their credit card then goes on your credit report, along with the hopefully excellent and lengthy record of repayment.

Once out of college, students will soon want to purchase a car or even their first house. If they have been careful to establish good credit while in college, it will mean paying a few hundred less per month in interest.

Don’t shun the plastic. Embrace it.

Ryan Johnson is a senior majoring in economics and international studies. He can be reached at letters@wildcat.arizona.edu