This widget is a public service provided by the Time and Frequency Division of the National Institute of Standards and Technology (NIST).  It is a web clock showing the official time of day from NIST, displayed as a 12 or 24-hour clock, in a user-selectable time zone.

The time reference for the widget is the output of the national time scale called UTC(NIST). It starts with a zero-offset time zone called Coordinated Universal Time (UTC), an
d it is adjusted to the local time based on the client's computer time zone settings.

It is not continuously linked to NIST - it re-synchronizes with NIST every 10 minutes. Therefore. this widget is intended as a time-of-day service only.  It should not be used to make measurements, nor should it be used to establish traceability to NIST.

The widget utilizes the client's computer clock as a timer to measure the round-trip network delay, which is the interval of time starting when the widget sends a time request to the server and ending when the time is displayed in the browser. The accuracy of the time shown will always be better than this round-trip delay.