Plain Text
Plain Text refers to data that is human-readable, and not protected by any cryptography transformation. It may be read and understood as is.
Plain text is the result of a cracking process, or deciphering, where the original data is crypted, and that transformation was lifted.
<?php
$plainText = 'PHP Rocks!';
$cryptedData = str_rot13($plainText); // cannot be read anymore
$plainTextAgain = str_rot13($cryptedData);
?>