¥Organized in a strict hierarchy with the universal type Object at
the top.
¥Every class C except Object
has an immediate superclass, which is the parent of
C in the hierarchy. In a class definition (like our Entry example), the default
superclass is Object.
¥ A descendant in the class
hierarchy is called a subclass. B is
a subclass of A iff A is a superclass of B. Entry is a subclass of Object; Object
is a superclass of Entry.