Originally, daylight saving was for agrarian societies, to get the most use out of as much daylight as you could. It was helpful with farmers and fisherman, but then, in later years, daylight saving was actually practiced for the sole purpose of saving energy.
It really first became official in World War I for growing extra food for troops over seas. It was brought back for World War II, but recently it was the Energy Policy Act of 2005 that was the real difference maker, that made it a more formal type of exercise with a few exceptions, that being Arizona, Hawaii, the U.S. Virgin Islands, Puerto Rico and the American Samoas.
If you were to take at the planet and you could light up places that were experiencing daylight saving, you'd really see a hop, skip, and a jump from one continent to another. It's really varied wherever you go. There are some places, I can tell you, in Africa, in many spots, where they don't practice it. Many parts in Asia. Europe practices it for the most part.