title: Setting a session variable on another server
body: <p>I am a newbie in PHP, I know how to set a session variable in my own website. I am trying to do this task where I need to set a session variable on another website that redirects to the login page on my website. Is it possible?
  If the question is still ambiguous, here is a better explanation. </p>
  
  <p>My website is on server A
  Another website is on server B
  A page on server B redirects the user to a page on server A. This page checks if the login details are correct. If they are, the page on server A sets a session variable. 
  However, when it redirects to server B after setting the session variable. The page on server B directs it back to server A notwithstanding the session set.</p>
  
  <p>Here is the code if you need to see it</p>
  
  <pre><code>if(!isset($_SESSION["user"]))
  {
  header("Location: http://serverA.com/login.php?w=serverB.com");
  }
  elseif (isset($_SESSION["user"]))
  {
  //do something
  }
  </code></pre>