What are the potential implications of activating register_globals in PHP, especially for a beginner?

Activating register_globals in PHP can lead to security vulnerabilities as it allows user input to automatically create global variables, potentially leading to injection attacks and data manipulation. It is recommended to disable register_globals and instead use superglobal arrays like $_GET, $_POST, and $_SESSION to access user input.

// Disable register_globals in PHP
ini_set('register_globals', 0);