AP Examination grades are reported on a 5-point scale from 1 to 5. This determines how well you performed, as it's curved, as well as whether a college should accept the score and give you credit. It's graded as follows:
5 — Extremely well qualified*
4 — Well qualified*
3 — Qualified*
2 — Possibly qualified*
1 — No recommendation**

  *qualified to receive college credit or advanced placement
  **no recommendation to receive college credit or advanced placement

You should know that even if you got a 1 on the AP, it's not the end of the world. Colleges don't see it, unless you show it to them. It's like the SAT's Score Choice System; if you don't want to show your score to college, nobody will make you.

You would want to for a couple reasons:

  • To brag to the Admissions Department how smart you are to take the class and get such a good score
  • To "place out" of a class. If you get a 4 or 5, most colleges will allow you to skip the Introductory classes for the department. If that's all you need, you could skip the requirement (ie. If you need to take 1 english class to graduate, the college will award you credit based on the AP score)

Not all high schools/secondary schools offer AP classes, so colleges will take this into account when you apply, to give you equal chance of acceptance along with students who have the opportunity.

International Baccalaureate (IB) classes are harder, but far fewer schools in the US offer them, though they are popular in Europe.