A credit score is used by banks and lending companies to make decisions on your loan applications. With a not so good credit score, you may get rejected for a loan or if you are lucky will be given a fraction of the amount that you are asking, for a higher interest rate and a shorter payment period.

A credit score, you see, determines whether a person is reliable enough to be given the money to as a loan. For although, they will be earning from you through the interest rates that they put on the loan, banks and lending companies are still cautious because they do know that they cannot just lend their money to people they don't know if able to handle money.
A credit score depends on a lot of factor. One of which is your reputation as a borrower. Are you always late in your payments for your credit card? Are you always knee deep in debt because you cannot seem to get around to paying each one until the interests were just too high?
Do you have maxed out credit cards? Have you had any other credit or loan that you have paid for or are still paying? How many are they? Have you had any problems paying for your loans? These will figure in the credit score that you will have.