$_POST

$_POST is an associative array of variables, transmitted to the current script via the HTTP POST method, with the MIME types application/x-www-form-urlencoded or multipart/form-data.

The received values are all strings or arrays. They are strings by default, and other scalar types needs a casting. The values are arrays when the URL uses the [] format.

$_POST is a superglobal: it is always available, in every scope.

Values inside $_POST are always strings, or arrays.

<?php

    // POST x=1
    $_POST['x'] === '1';

    // POST y=abc
    $_POST['y'] === 'abc';

    // POST z[]=def
    // POST z[]=ghi
    $_POST['z'] === ['def', 'ghi'];

?>

Documentation

See also How To Use The $_POST[] Variable In PHP.

Related : $_GET, $_REQUEST, $_COOKIE, $_ENV, $_SERVER, Form, Incoming Data