First we have to know how the whole credit industry works…

Credit bureaus are companies that gather and sell information about a person’s credit data. They sell credit data on consumers to banks, mortgage industry  credit card companies, department stores, auto dealers, insurance industry, property owners, and any employers. In turn the above companies use the data to decide on applications for credit, any insurance, housing, and even employment.

Credit bureaus also provide identifying data about consumer name, address, prior address, work place and former employment information to government entities  If a government entity is considering giving credit, checking the status of an account, or trying to collect a debt, giving a license or other any benefit, the government entity will get the credit report.

The 3 major bureaus are : Equifax , Experian , and Transunion .
Innovis has come to the scene recently.
There are also many affiliates credit reporting agencies which are mostly run or controlled by the 3 major bureaus.
Check the rest on abcdone.com