Aside from your Social Security Number, your credit score may be the most important number to know in order to help you get any form of loan. Your credit score tells banks and other lenders your creditworthiness and whether or not you are likely to repay your debts based on your previous payment history, along with your current lines of credit and the usage of these accounts. The higher your credit score is, the more likely you are to be granted your applied loan, and generally for a lower interest rate.
Though the factors that determine your credit score are rather complex, the main factors that determine your score are on-time payment history, amount of current debt, length of credit history, forms of credit, and credit inquiries. Any derogatory marks on your credit history (bankruptcy, foreclosure, etc) will have a profound impact on your report for many years to come.