title: Why does the Ruby module Kernel exist?
body: <p>In the book <em>OO Design in Ruby</em>, Sandi Metz says that the main use of modules is to implement duck types with them and include them in every class needed. Why is the Ruby <code>Kernel</code> a module included in <code>Object</code>? As far as I know it isn't used anywhere else. What's the point of using a module?</p>