title: Difference between gem and require (require open-uri)
body: <p>I just wanted to understand for my self.</p>
  
  <p>I'm using the nokogiri gem (for parsing HTML). If I got it right to open URLs I need to use a method from the gem 'open-uri'.</p>
  
  <p>But when I include it in my Gemfile (on Windows developer's machine):</p>
  
  <p><code>gem 'open-uri'</code> - there is an error while bundle install that it can not find gem.</p>
  
  <p>So If I use <code>require 'open-uri'</code> - its working.</p>
  
  <p>So can some explain what is going on?</p>