AP Calculus
The AP Calculus course is normally taken in America, but many secondary schools outside the United States offer authorized AP courses. AB and BC are each equivalent to one semester of college calculus courses (Calculus I and Calculus II respectively). As such, the main prerequisite for both AB and BC Calculus is PreCalculus.
AB Calculus is the first part of a Calculus course. BC Calculus, which includes everything in AB Calculus, plus seven extra topics, is a tougher, second part. Many students do AB Calculus followed by BC Calculus, but it is also possible to do only one of these units individually. You'll actually get an AB Calculus subscore when you take the BC exam.
The topic list for AB Calculus is:

Limits and Continuity

Differentiation: Definition and Fundamental Properties

Differentiation: Composite, Implicit, and Inverse Functions

Contextual Applications of Differentiation

Analytical Applications of Differentiation

Integration and Accumulation of Change

Differential Equations

Applications of Integration
BC Calculus additional Topics:

Partial Fractions

Parametric Equations

Integration by parts

Logistic Equation

Polar Coordinates

VectorValued Functions (motion in a plane)

Infinite Sequences and Series
AP Calculus AB and BC past papers are available including full papers, multiple choice and free response questions from 1969 onwards.