title: Better Understanding of PHP $_POST superglobal
body: <p>I'm just getting started with PHP and I've found that no matter where I look online, I can't find any in-depth explanation of how the $_POST superglobal actually works.</p>
  
  <p>I get the basics that the $_POST superglobal is an associative array that can be accessed anywhere within a script, and that it holds values received through post requests. My questions are: is it universal to all PHP files on a website? If not, how do you specify which file on the website you want to post data to, or transfer something received by $_POST to another file? How do you make a code that waits for data to be sent to a certain index in $_POST (ie, $_POST["name"]) before doing something with that data, so that your code doesn't immediately set a variable equal to the aforementioned post index which is null before receiving the request?</p>
  
  <p>I ask these questions because I'm finding that although I have no problem using $_POST when it comes to form handling, I can't get anything to work with $_POST when I send the post request externally, such as from a program like Fiddler. I've tried sending post data in the "application/x-www-form-urlencoded" format to my testing website hosted by a free website hosting service and no matter what I do, I always end up with $_POST["name"] (yes, the data I'm sending is properly written as being "name=test") being of type NULL in every file on my site, making it therefore not possible for me to store this sent data in my SQL database.</p>