In an Ubuntu system, root is the superuser, the owner of most system files. Questions about the root user or accessing superuser privileges may use this tag; the / or /root directories may be more appropriately tagged with "filesystem"
root is the name used for the super user account in Ubuntu, which has all permissions to control files and directories in the system. The privileged status of this account is associated not with the name "root" but with its UID - root is UID 0
The majority of system files belong to root and normal users do not have permission to modify them. This makes the system more secure, as it is difficult for an unprivileged user to cause serious damage.
In Ubuntu, by default there is no password for root. This means that you cannot su root (switch user to root) as this would require root's password. Instead of switching user to root or logging in as root, normal users can elevate privileges using the sudo (superuser do) command. By default, the first human user account created will have UID 1000 and the right to run any command with sudo privilege. Other user accounts may be granted this permission, and other options may be configured, using the /etc/sudoers file, which should always be edited with the visudo command.
Related tags: sudo permissions
