'sudo' is a command that allows users to execute some commands as root. The /etc/sudoers file (edited with 'visudo') specifies which users have access to sudo and which commands they can run. 'sudo' logs all its activities to syslogd, so the system administrator can keep an eye on things. Sudo asks for the password for initializing an check period of a given time N (where N is defined at installation and is set to 5 minutes by default).