title: Immutable vs Unmodifiable collection
body: <p>From the <a href="http://docs.oracle.com/javase/8/docs/technotes/guides/collections/overview.html" rel="noreferrer">Collections Framework Overview</a>:  </p>
  
  <blockquote>
    <p>Collections that do not support modification operations (such as <code>add</code>, <code>remove</code> and <code>clear</code>) are referred to as <em>unmodifiable</em>. Collections that are not unmodifiable are <em>modifiable</em>.</p>
    
    <p>Collections that additionally guarantee that no change in the <code>Collection</code> object will be visible are referred to as <em>immutable</em>. Collections that are not immutable are <em>mutable</em>.</p>
  </blockquote>
  
  <p>I cannot understand the distinction.<br>
  What is the difference between <em>unmodifiable</em> and <em>immutable</em> here?  </p>