Daylight saving time (DST) is a misnomer. There is actually no daylight being saved. In effect, what happens during daylight saving time is that an hour of daylight is moved from the morning to the evening according to the clock. The sun remains in the heavens and the world spins at the same rate, as always.
Daylight saving time was first suggested by Benjamin Franklin in an amusing essay he wrote for his friends in Paris. The essay suggested that Parisians could save money on oil lamps by changing their sleeping and waking habits to correspond more with the sun. The idea was adapted in 1907 by Londoner William Willett in his pamphlet "The Waste of Daylight." Willett suggested turning the clocks ahead in the spring to take advantage of the extra hours of daylight at a time of day when people were actually awake to enjoy them.
Although Willett lobbied for his scheme, he was not successful and he died in 1915, never having seen his idea come to fruition.
It was not until May 17, 1916 that Willett's concept was instituted in England. Even then, it met with strong opposition.
The concept of DST has had a long and varied history, causing boons and disasters in economics and laws of inheritance and confusion almost everywhere.
One source of confusion is that DST is not carried out everywhere, and when it is there are differences in how and when it is practiced. For instance, in the US DST begins on the second Sunday in March and ends on the first Sunday of November. In the European Union (EU), Summer Time as it is called, begins on the last Sunday in March and ends on the last Sunday in October. Even within the US, there are places that do not observe DST. The time that the change occurs is also not universal. In the US, the clocks are changed at 2AM and in the EU at 1AM.
Because countries on or near the equator have about 12 hours of daylight throughout the year, DST makes little difference. However, many of these countries observe DST anyway, in order to keep the time zone differences between their country and other countries the same.
Daylight saving time observance has had some surprising and unexpected consequences.
In 2007, the US made a law extending DST to the first Sunday in November. This change was conceived to help lower the number of pedestrian traffic deaths that occur when children go trick-or-treating on Halloween. Now there would be an extra hour of light to keep the kids safe. This change in the law was an inadvertent boon to the candy industry, since more young children, who are not allowed out after dark, were able to trick-or-treat longer.
Ben Franklin's lampoon of his own frugality and the sleeping habits of Parisians has had a huge effect on the world.