A credit score is a single number calculated from various credit report data that serves as a guide to lenders and other subscribers — including employers — on how creditworthy a person is. The first credit scoring system was created in the 1990s by a Minnesota company called Fair Isaac Corp., creator of the FICO score. The higher your score, the more attractive you are to lenders. There have been other brands of credit scores that have come and gone, but Fair Isaac Corp. and FICO are clear leaders in the field.

It's estimated that roughly 75 percent of the U.S. population that's eligible for borrowing has an up-to-the-minute credit score. Credit scoring has now been around for forty-five years, and the consensus is that it's helped make lending fairer. An estimated 4.5 billion pieces of data go into credit records each month, and more than 1 billion consumer credit reports are issued annually in the United States.

Like credit reports, credit scores are being examined by many organizations that have nothing to do with your credit. Employers can obtain your median credit scores with a copy of your three credit reports, and increasingly, insurers are pulling credit reports and scores as yet another way to assess you as a risky customer.

Unlike the free samples of your three credit reports that you can get once a year, you're going to have to pay to see your credit scores — unless you sign up for a free trial of the credit score review services at MyFico.com or at the three credit reporting agencies and remember to cancel those services before the thirty-day trial period runs out.

You have four choices of places to buy your credit score, which will cost you between $6 and $16. You can buy the proprietary scores kept by the three credit reporting companies, or you can use MyFico.com, which is the credit score site run by Fair Isaac Corp. The three credit services have also developed a new scoring mechanism called VantageScore, but it hasn't shown signs of toppling FICO yet.