title: Ruby: what does :: prefix do?
body: <p>I was reading through the source of <a href="https://github.com/wycats/artifice" rel="noreferrer">Artifice</a> and saw:</p>
  
  <pre><code>module Artifice
    NET_HTTP = ::Net::HTTP
    # ...
  end
  </code></pre>
  
  <p>line: <a href="https://github.com/wycats/artifice/blob/master/lib/artifice.rb#L6" rel="noreferrer">https://github.com/wycats/artifice/blob/master/lib/artifice.rb#L6</a></p>
  
  <p>Why not just do <code>Net::HTTP</code> instead of <code>::Net::HTTP</code>, i.e., what does it mean when you use <code>::</code> as a prefix?</p>