It is the primary management command for the NTP time server.

It updates the local system's date (i.e. day, month and year) but not the time (i.e. hours, minutes, seconds).

It queries one or more NTP time servers and adjusts the system time accordingly.

It sends the local system time to one or many remote NTP time servers for redistribution.

It can be used by any user to set the user clock independently of the system clock.