Root or administrator privileges
Some commands used to manage a computer must be executed by an administrator user or the root user. If you get a message such as “permission denied,” the command probably requires root privileges. You can execute one command at a time as the root user, which is implicitly an administrator, by beginning each command with sudo.
For example:
sudo passwd newuser
To use sudo, you must be logged in as an administrator. If you haven’t used sudo recently, you’re prompted to enter the administrator password.