Daylight Saving Time begins this weekend so set your clocks ahead one hour by 2am Sunday.
The concept of "saving daylight" was first proposed by Benjamin Franklin in 1784. Its main purpose to make better use of daylight.
The plan was not formally adopted in the U.S. until 1918 as a wartime conservation measure. It was widely unpopular mostly because people then rose earlier and went to bed earlier than people do today. After the war ended, the law was repealed only to return as "War Time" in 1942.
It finally became official federal law in 1966.
Nevertheless, Arizona and Hawaii don't observe it.