AP's are not really part of the HS curriculum. You take an AP-level class, which is like a HS class with college level material, subject matter, and they expect you to understand the stuff like you are in college. Where I go to school, AP's are optional, so you can take the class, get your HS credit, and thats it. But if you take the AP exam and do well, many colleges will accept AP credit as if you had taken the class. So you start off college with credits. So that is why people take the exams. But only AP-level classes have them. Classes that don't have an AP have a final exam at the end of the year....or in New York State, we have Regents exams which is a whole different story. So I took 1 AP class last year, 4 this year, and 3 next year.