: It could automatically attempt a safe, non-invasive test (like adding a single apostrophe ' to the ID) to see if the server returns a verbose SQL error.

: The PHP script typically uses $_GET['id'] to capture the value "1" and include it in an SQL query like SELECT * FROM table WHERE id = 1 .

Once you have a URL (e.g., ://example.com ), security researchers perform a "break test" to see if the database is poorly protected: : Change the URL to ://example.com' . Analyze the result :

: Many sites use "Pretty URLs" (e.g., /user/1 instead of user.php?id=1 ) which hides the underlying technology.