running linux loged in as root is BAAAD, it is about only way to get viruses/trojans/malware in Linux, and too big risk to trash system if you do anything wrong, using "sudo" or even better "su -c" is MUCH safer, you can still crash things but you have one extra level of safety.

sudo is a way to do one single task as root, say open kedit to edit fstab, if you type comand below in konsole (in GUI) that will open kedit as root with fstab already opened.
Code:
sudo kedit /etc/fstab
or you could type
Code:
su -c "kedit /etc/fstab"
that will do same thing, su -c "command" is basically ask for root password, if correctly entered give me rootprivileges for comand between " " .