A credit score summarizes your entire credit report information into one number. This number is calculated by a mathematical equation that evaluates many types of data points (score factors) from your credit report at that particular credit-reporting agency.
There are many types of score factors that can have a positive or negative effect on your score. The factors are listed in order of the degree to which they affect your score negatively, meaning that the factor listed first is what most decreased your score.
Some examples of score factors include but are not limited to:
Too many inquiries (how often you apply for credit)
Too many serious delinquencies (how timely your account payments are)
Too many recently opened accounts (how often you have opened new lines of credit recently)
The average balance of revolving accounts is too high (what you owe vs. available)
Too few mortgage accounts (what types of credit do you use)