Debugger

A debugger is an extension or an external program that is used to help when searching for bugs in PHP code.

There are several debuggers in PHP : Interactive PHP Debugger, xdebug, kint, krumo, whoops, PHP.

Debugging include executing the code step by step, displaying and modifying the content of variables.

<?php
     // simple debug system with native PHP print_r
     print_r($_GET);
?>

See also Xdebug, Interactive PHP Debugger, Kint, Whoops, Krumo