Seeing a URL like https://facebook.com in your browser address bar is common, but it can look a bit suspicious if you aren't familiar with how web servers work.
After a successful login, the system might redirect you from the login page to the home page using this parameter to signal that the authentication was successful. Why "home.php"? https facebook com home php _rdr
While Facebook has modernized most interfaces, this specific URL and the pages it loads still offer a few useful features, particularly for users looking for a simpler experience or specific troubleshooting tools. Seeing a URL like https://facebook