How To Log in Computer Without Password

Hello friends, how @ all hope well. Today I am getting discuss something new. Log in a computer without password, someone things how does it possible or its seems some hacking software or others but its not, its just a technique. Whenever you log in your computer just press Alt + Ctrl + Delete together for two times or if comes windows like up. You have to type Administrator on user name than press Enter. You have to log in now without password.  This is visual system of operating may be only xp (coz i don't try this to windows 7 bt u can). You could block this system for more secure your computer, for this you have to log in at first by that way and go to Start > Settings > Control Panel and Click User Account, Click Administrator and create a password now your computer is more secure no one can enter your computer by that way without password.  Thanks at all agian. And don't miss me to give a comments.