The higher your credit score, the lower you can reduce the interest rates you're paying to all of your creditors—mortgage lenders, auto lenders, credit card companies. If you're in debt, then servicing those debts takes a big chunk out of your monthly nut. A high credit score can make that chunk as small as possible.
And because what it really is, for lack of a better description, is a snapshot of your borrowing and bill-paying behavior over the previous 24 months, as time goes by you have the power to change it for the better.
35% of your score is based upon how well you pay your bills.
30% of your score is a measure of how much credit you have available to you and how much of that credit you're using.
10% is based on your search for new credit—how recently have you opened (or inquired about opening) new accounts?
10% is the composition of your file. What percentage of your file is bankcard debt and what percentage is installment debt?
15% is a measure of the length of your credit relationships. How long have you had the cards in your wallet?
Advice on raising your credit score