Ever wonder how a creditor decides whether to give you credit?

For years, creditors have been using credit scoring systems to determine if you'd be a good risk for credit cards and auto loans.

A credit score is a three-digit number used to determine credit risk.

That number will range from 300 to 850.

The best number to have is 720 or above, according to Fair Isaac Corp., a California-based company that developed the credit score.

The higher the credit score, the better someone looks to lenders.

High scores open the door to low-interest rates for things like cars, credit cards and home loans.

Donald Rehorn, of Sacramento, Calif., County Consumer Credit Counseling, says there is some confusion about what affects credit scores.

"Most people are really concerned about the inquiries to their credit. They think that has a big detriment. And of the things that affects it, that is the least," Rehorn said.

Late payments and too much debt hurt scores the most.

Rehorn says the best way to boost your credit score is by paying bills on time with checks that won't bounce.

Rehorn also says it is important to look at your credit report every year and check it for errors.

For specific steps on improving your credit score, check out Boost Your Credit Score.