Classes are Objects

irb_session.rb

self
#=> main
self.class
#=> Object
self.object_id
#=> -595331298

o = Object.new
#=> #<Object:0xb940af38>

# A Ruby object has a class
o.class
#=> Object

# objects are a class in Ruby
Object.class
#=> Class

Class.superclass
#=> Module

Class.superclass.superclass
#=> Object

Class.superclass.superclass.superclass
#=> BasicObject

Class.superclass.superclass.superclass.superclass
#=> nil

Object.superclass
#=> BasicObject

Object.superclass.superclass
#=> nil