What is the correct syntax for accessing global variables like $_POST in PHP?

When accessing global variables like $_POST in PHP, it is important to use the correct syntax to avoid errors. To access the value of a variable stored in $_POST, you need to use the $_POST superglobal followed by square brackets containing the name of the variable you want to access. For example, to access the value of a variable named "username" submitted via a form using the POST method, you would use $_POST['username'].

$username = $_POST['username'];