Obfuscation

Obfuscation refers to the practice of deliberately making something difficult to understand or obscure. In the context of web security, code obfuscation is a technique used to make source code more difficult to filter and identify as a threat. The primary goal is not to improve the program’s functionality but rather to hinder reverse engineering, the extraction of sensitive information from the code.

<?php

    // built with base64_encode($_GET);
    $v = "X0dFVA==";

    // obfuscated code : this displays $_GET
    print_r($\{base64_decode($v)});

?>

See also Obfuscate Your PHP Source Code.

Related : Minification, Proprietary Source