Another brief decription:
History
Although first instituted in 1915, the idea of daylight time had been batted around for more than a century. Benjamin Franklin suggested the idea more than once in the 1770s while he was a minister to France. But it wasn't until more than a century later that the idea of daylight time was taken seriously.
William Willett, an English writer revived the idea in 1907, and eight years later Germany was the first nation to adopt daylight time. The reason: energy conservation. Britain quickly followed suit and instituted British Summer Time in 1916.
Several areas, including parts of Europe, Canada and the U.S., followed suit during the First World War. In most cases daylight time ended with the armistice.
During the Second World War, a different form of daylight time was reinstated by Britain and clocks were set two hours ahead of GMT during the summer. It was known as Double Summer Time. The time shift didn't end with the summer, as clocks were rolled back to be one hour ahead of GMT through the winter.
The Uniform Time Act, enacted by the U.S. Congress in 1966, established a system of uniform (within each time zone) daylight time throughout most of the U.S. and its possessions, exempting only those states in which the legislatures voted to keep the entire state on standard time.