Credit, by one broad definition, is your ability to borrow money or secure goods or services while agreeing to pay later. The amount and type of credit available to you is determined by your three-digit credit score. FICO scores are the most common credit scoring system used by more than 90% of financial institutions. FICO scores range from 300 to 850. Scores below 580 are considered poor. Anything above 740 would put you into the range of very good to exceptional credit. Customers with scores in this range qualify for the best interest rates and offers.It's important to maintain a high credit score, or work to improve a lower score, because the score dictates what interest rate -- the amount you're charged by a lender to borrow its assets -- you'll receive when taking out loans or applying for credit cards. The type of deals offered for cell phone plans, insurance products, or deposits required for utilities, for example, also can be affected by your credit score. The lower your score, the more you will pay, as creditors deem you as a high financial risk.Let say, for example, that you finance a $10,000 used car over 48 months. Customers with excellent credit scores (typically 750 or more) would qualify for an average rate of 8.18%. You will pay $245 a month and $1,759 in interest over the life of the loan. Car buyers with fair credit scores (600-699) are looking at average interest rates of 14.89%. A seven point interest rate jump will increase your monthly payments to $278 per month for a total of $3,332 in interest over the life of the loan. A 51-point drop from 750 in your credit score could cost a buyer an additional $1,573 in interest for the exact same vehicle. Maintaining the highest possible credit score allows you to access credit at the lowest rate. Healthy credit affects your bottom line directly.