Inheritance is a mechanism for code reuse in object-oriented systems. In a class-based system such as Smalltalk - and hence Squeak - it means a relationship between two classes A and B, such that class A is considered to be the parent (or superclass) of class B (the subclass or child of A). The subclass B initially can be thought to have the same state variables and methods as class A. Subsequently, in subclass B can be added new state variables and methods, and the methods which B has gotten (it is said: inherited) from A can be overridden, i.e. new behavior can be added or behavior can even be changed completely.
