predefined.php

Example: $_SERVER['HTTP_USER_AGENT']
This example returns the client's web browswer

Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)

Example: $_SERVER['SCRIPT_FILENAME']
This example returns the file path of the current file that is being executed.

/home/rodri895/public_html/week3/assignment3/predefined.php

Explanation:

Predefined variables are variables in PHP that have pre established actions that can be called anywhere within a script. This is because predefined variables are global variables but do not need to be specified as such because predefined varaibles are global variables by default.