The three major credit bureaus in the United States are Equifax (based in Atlanta), Experian (based in Costa Mesa, California), and TransUnion (based in Chicago). There are many credit monitoring services which help you to escape from being a victim of fraud by alerting you about the slight changes in your credit daily or weekly by referring to credit bureau reports.
The three credit bureaus differ in their processes of determining the credit score according to the retrieval of information, and report of information. The three major credit reporting agencies determine their own FICO (Fair Isaac