assuming you mean personal credit, there are 3 private companies that rate your credit on a scale from around 300 to 900 or so....if you score above 720 on this scale you pretty much get approved for anything at the best interest rates if you have the income. Below this level, your interest rates begin to increase and your acceptance level will drop.
if you don't have any credit cards, car payment, etc., you have no rating at all. if you pay your bill late, your rating will be at the low end of the scale, and you will have to pay higher interest rates on borrowing for money, you will be able to borrow less and may get turned down.
there is a simialr thing for companies called your D&B rating - same idea.
hope that helps!
