Federal Law mandates that your credit report be made available to you freely on an annual basis. The three credit bureaus, Experian, Equifax and TransUnion all make your annual reports available at https://www.annualcreditreport.com/cra/index.jsp. You are able to get one free report at a time, but keep in mind your other reports most likely will be reporting data the one you received don't.
Your credit report and your credit score are different. FairIsaac Corp developed the FICO score, the most commonly used credit score. The FICO score is a number between 350 and 850 that predicts how likely you are to become 90 days late on a loan. You can purchase your FICO score for all three credit bureaus, or just for one, at http://www.myfico.com.
As credit scores became more and more important to the everyday person's life, it became apparent that some laws governing the credit bureaus were needed. The Fair Credit Reporting Act (FCRA) is the law that governs the credit bureaus and protects consumers.
The credit bureaus have a lot of helpful information on their sites about credit, and the ability to purchase reports if you have already received your free report for the year.