title: how can php know which html-file called it
body: <p>If we have 2 html files (i.e. one.html and two.html) and within both we have a form which calls the same php file on submit, like:</p>
  
  <pre><code>&lt;form method="post" action="example.php"&gt; 
  </code></pre>
  
  <p>, how can example.php know which html file called it?</p>
  
  <p>I'm new to php so any comments are appreciated.</p>