There are three major credit agencies which track all of your credit history including loans, credit cards, etc. They also have records of delinquencies in payment and any defaults that you have made. Think of your credit report as similar to an education transcript - however, on this transcript, the creditors you have report on your payment behaviors.
Major Credit Reporting Agencies
The Federal Trade Commission's Fair Credit Reporting Act and the FACT Act allow you to request a free credit file disclosure, commonly called a credit report, once every 12 months from each of the nationwide consumer credit reporting companies: Equifax, Experian and TransUnion.
Want a Free Annual Credit Report? The only official website is annualcreditreport.com. Many other sites require payment for the same information!
If you are concerned about your credit score, you may get a report with your score from the agencies listed above - but there is generally a fee to access your official FICO score along with your credit report from these agencies. If your credit history is like a transcript, then your credit score is like the GPA. If your report is good, your score will be too. The reason you may want to see your score is that any new credit you are seeking (not Direct Unsubsidized Loans for education, however) will use this score to decide your credit-worthiness. This will help them determine the interest rate they are willing to extend to you. Some credit cards, spending tracking applications, etc., will offer you a "free score," if you use their products; some are actual FICO scores and some are approximated scores. Often these score services offer you education and information on improving your score. You can learn more about scores and how to improve them here.