You are graded on how you manage your credit. It is like being in school. You will have a good or excellent credit score if you manage your credit well. If you are not good at managing your credit and miss payments, you will have a bad or poor credit score. Landlords and mortgage lenders have their standards for acceptable credit scores. They also reject applicants who do not meet their credit score requirements. To avoid being told your application was not approved because of your credit, know your credit score beforehand.