Cannot login as root on Debian
 

When I start Debian, the login window does not let me login as root. How can I do it?

You don't. There's probably a way to enable it, but it's really not a good idea to run as root in a graphical environment. What's wrong with using your user account and then "becoming" root (e.g. with the su command) for things you need to run with root privileges?

Assuming you're using Gnome, in GDM look for the Actions Menu, select Configure|Security and authorize "root" to log on there.

Nylex is right, tho. This is not a very good idea. The only time I use it is when I want to do housekeeping on directories in /usr that contain pictures I need to see before I delete them, or to check programs I'm having trouble executing as a regular user to make sure it's not a permissions issue, etc. Then as soon as I'm done I log out of root.

In some ways, it's even easier to make a major mess using root from graphical mode than from the command line.

"root" in Linux is like owning a big power saw.
It's good to have it.
It's good to be able to use it.
It's NOT good to use it for every task.

I use GUI as root quite regularly---I also use power saws. The latter will do infinitely more damage if used carelessly. With caution, both can be used safely.

Slightly off-topic, but I get a kick out of newbies who use root indiscriminately. Sooner or later, they are going to wind up blowing out their system, probably losing a few things they really wanted in the process. Talk about a real learning experience, that is one.

People who switch to Ubuntu generally dislike the sudo business a lot. Ubuntu is trying to protect me from a lesson I've already learned.