title: What is the meaning of $this
body: <p>I've seen some scripts contain <code>$this</code> in a PHP script that has OOP, I never knew the meaning of it... like</p>
  
  <pre><code>$this-&gt;refresh();
  </code></pre>
  
  <p>Perhaps explain to me what <code>$this</code> refers to be...?</p>
  
  <p>But I do know that you cannot use it as a dynamic variable like <code>$this_is_a_variable</code> but why can't use it as a dynamic variable? </p>