Daylight Saving Time

Daylight Saving Time (United States)

Daylight Saving Time (United States) 2018 begins at 2:00 AM on Sunday, March 11 and ends at 2:00 AM on Sunday

What is daylight saving time?

Daylight saving time, or DST, is the period of the year when clocks are moved one hour ahead. In the United States, this has the effect of creating more sunlit hours in the evening during months when the weather is the warmest. We advance our clocks ahead one hour at the beginning of DST, and move them back one hour ("spring forward, fall back") when we return to standard time (ST). The transition from ST to DST has the effect of moving one hour of daylight from the morning to the evening. The transition from DST to ST effectively moves one hour of daylight from the evening to the morning.

DST was formally introduced in the United States in 1918. Today, most of the country and its territories observe DST. However, DST is not observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and the state of Arizona (with the exception of the Navajo Indian Reservation, which does observe DST).

Spring forward, Fall back
During DST, clocks are turned forward an hour, effectively moving an hour of daylight from the morning to the evening

Spelling and grammar
The official spelling is Daylight Saving Time, not Daylight SavingS Time.

In the European Union, Summer Time begins and ends at 1:00 a.m. Universal Time (Greenwich Mean Time). It begins the last Sunday in March and ends the last Sunday in October. In the EU, all time zones change at the same moment.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

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