gistfile1.rb

class Foo
  # an instance method, added to Foo's method table (added to Foo)
  def foo
  end

  # a class method, added to Foo's singleton class (because only classes can
  # store methods, so a class method must be a method on "the class's class")
  def Foo.foo
  end

  # a class method, added to self's singleton class (in this case, self is Foo:
  # self could also be a subclass)
  def self.foo
  end

end