Auto Login ubuntu

Its a good idea as after doing this system will not ask your login password at the time when you login to your system which can save your time, but from security point it is really not a very good idea as the users who have physical access to your computer can get into your computer without any password.
You can set this in ubuntu go to

System>>Administration>>Login Window (after clicking on Login Window option it will ask you for password)

now it will display Login Window Prefrences where we need to choose security tab and click on Enable Automatic Login.
thats it, from now on your ubuntu will not ask for any username or password at the time of booting.