Module

# module "Destructable"
module Destructable
  def destroy(obj)
    puts "destroying object.."
  end
end

class Material
  include Destructable
end

# example
table = new Material
table.destroy # "destroying object.."

In above snippet, we can call destroy method from instance of Material class even if we didn't specify the destroy method in Material class. This is because we use the definition of destroy method via Ruby module.

The way it works is, we define set of methods inside module and include it in any class, where we want to use it by putting include keyword, just like in above snippet.