title: Mobile App Unique ID detection in PHP
body: <p>I'm building a mobile app which will call a search engine on my website.  I have PHP code to detect if a person is coming in through a Mobile device.  However, I want to see if I can detect if they are coming in through my app versus a regular page browse.</p>
  
  <p>In the past, I've had a hidden field on a form submission, but this is not feasible anymore.</p>
  
  <p>I want to know if there is a way if somebody accesses a page on my website through the mobile app or a mobile browser?</p>
  
  <p>One option is to pass a PHP $_GET parameter, but I'm looking for other solutions.</p>