Daylight Saving Time (DST) is the practice of setting the clocks forward one hour from standard time during the summer months (=lose 1 hour), and back again in the fall (=regain 1 hour), in order to make better use of natural daylight. So "spring forward, fall back" is one of the little sayings used to remember which way to set your watch.
In 1966, Congress passed the Uniform Time Act, which standardized the length of DST, which begins on the second Sunday of March each year and ends on the first Sunday of November. In 2021, Daylight Saving starts at 2 a.m. on March 14 and it will end at 2 a.m. on November 7. In other words, sunrise and sunset will be about one hour later on March 14 than the day before, meaning there will be more light in the evening.
Benjamin Franklin is often credited with first proposing daylight saving in his 1784 essay, An Economical Project. The idea wasn't seriously considered, however, until more than a century later when William Willetts, a British builder, fiercely recommended it. The current DST format was proposed in New Zealand by entomologist (昆虫学家) George Hudson. In 1895, he recommended a two-hour time change because he wanted to have more daylight after work to go hunting for bugs in the summer.
Some studies show that DST could lead to fewer road accidents and injuries by supplying more daylight during the hours when more people use the roads. It is also used to reduce the amount of energy needed for lighting during the evening hours. However, other studies claim that people's health might suffer due to DST changes.
Nearly every state in the U.S. observes DST, according to the Department of Transportation. However, Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and most of Arizona do not.
