Use PDO or MySQLi in PHP to prevent SQL injection.
In the early days of the web, many developers didn't "sanitize" these ID parameters. If a site is poorly coded, an attacker can replace the 1 with a malicious SQL command. If the server executes that command, the attacker could steal user data, passwords, or even take control of the entire website. inurl php id 1 free
Finding "hidden" or "free" versions of premium content. Use PDO or MySQLi in PHP to prevent SQL injection