title: What is the purpose of webpack [hash] and [chunkhash]?
body: <p>Could somebody tell me what is the the purpose [hash] and [chunkhash] and where do they come from?</p>
  
  <pre><code>output: {
      path: "/home/proj/cdn/assets/[hash]",
      publicPath: "http://cdn.example.com/assets/[hash]/"
  } 
  </code></pre>