What is the purpose of $_POST?

I know it is php global variable but I'm not sure, what it do? I also read from official php site, but did not understand.

Solution

You may want to read up on the basics of PHP. Try reading some starter tutorials.

$_POST is a variable used to grab data sent through a web form.

Here's a simple page describing $_POST and how to use it from W3Schools: PHP $_POST Function

Basically:

Use HTML like this on your first page:

<form action="submit.php" method="post">
  Email: <input type="text" name="emailaddress" /> <input type="submit" value="Subscribe" />
</form>

Then on submit.php use something like this:

<?
  echo "You subscribed with the email address:";
  echo $_POST['emailaddress'];
?>