title: Show message with PHP when a parameter is passed in the URL
body: <p>As new in PHP, I have a simple question. Am I able to do something like this?</p>
  
  <p>E.g. the user, is redirected to a link like this:</p>
  
  <p><a href="http://website.com/directory?parameter" rel="nofollow">http://website.com/directory?parameter</a></p>
  
  <p>When that parameter is in the URL, I want a message to appear somewhere in the website, when the parameter is missing, just hide it.</p>