It starts with your financial activities. You can establish and modify your line of credit by getting credit cards or shopping cards, taking out loans and mortgages from banks or other financial institutions, and paying your bills. Your credit providers then submit your credit information to a credit reporting agency such as Equifax, Experian, or Trans Union.
The credit reporting agency will take your credit history and compile it, using it to calculate your credit report score. After this, the agency allows any persons or institutions with proper authority (including yourself) to view your credit score and history.