title: PHP and AJAX security question
body: <p>I am currently building a web app in which PHP files are loaded into a main file using jQuery's $.ajax function. However, the PHP files are obviously still accessible outside of the app, by just typing the files name in the address bar.</p>
  
  <p>So my question is what would be the best way to make it so that the PHP file being 'ajaxed' in knows that it is contained in the correct page and will function correctly, but if it is accessed in any other way (even if someone were to make they're own website and AJAX in my PHP file) then the file should say "access denied" or something.</p>
  
  <p>Thanks in advance</p>