By default, the root account password is locked in Ubuntu. This means that you cannot login as root directly or use the su command to become the root user. However, since the root account physically exists it is still possible to run programs with root-level privileges. This is where sudo comes in — it allows authorized users to run certain programs as root without having to know the root password. If you are, for some reason, logging in as root, please first follow step 1 and 2.