Rich Text

Rich Text refers to data that is human-readable, yet includes extra information to apply style to that text, such as paragraph, section, font, bold, italic, etc.

Such text is not crypted, per se, yet requires a specific reader to make the reading experience pleasant.

HTML, XML, RTF are all examples of Rich Text file.

<?php

    $plainText = 'PHP {\bRocks!}'; // Rocks! is in bold, according to RTF

?>

Documentation

Related : To Crypt, Plain Text, PDF, Text