title: Creating and deleting instance variables
body: <p>In file <code>index.html.erb</code>, I have code that prints some properties of each element of <code>@calender_items</code>:</p>
  
  <pre><code>&lt;% @calender_items.each do |calender_item| %&gt;​
    ...
    &lt;td&gt;&lt;%= calender_item.date %&gt;&lt;/td&gt;
    ...
  &lt;% end %&gt;
  </code></pre>
  
  <p>The instance variable is assigned by this line in a controller:</p>
  
  <pre><code>@calender_items = CalenderItem.all
  </code></pre>
  
  <p>If I comment out the this line, <code>index.html.erb</code> file still functions. Can someone give me any hints on why I can still access the instance variable even though it is no longer assigned? When do instance variables get destroyed?</p>