when is day light savings?

Answer 1

A method to conserve power.

According to Wikipedia: http://en.wikipedia.org/wiki/Day_light_savings_time
"Daylight saving time (DST; also summer time in British English) is the convention of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn; several ancient cultures lengthened each summer daylight hour instead. Modern DST was first proposed in 1907 by William Willett, and saw its first widespread use in 1916 as a wartime measure aimed at conserving coal. Despite controversy, many countries have used it since then; details vary by location and change occasionally."

The convention to remember it is:
Fall backward
Spring forward

Recently, the US Congress advanced the time of daylight savings time in an attempt to save money; however that was wiped out by the required time and money to reprogram computers to make the change. Old operating systems still have to be changed manually. That's what happens when you don't think something through.

Answer 2

In most of Canada and the US, Daylight Saving Time begins on the second Sunday in March. On the first Sunday in November areas on Daylight Saving Time return to Standard Time.
In the U.S., each time zone switches at a different time.
In Canada, each time zone switches at 2:00 am local time.

Answer 3

Like Dan S said, it set arbitrarily by the government. It doesn't actually have anything to do with astronomy. The purpose was originally to save fuel, but these days it's usually to save lives in vehicle wrecks.

Answer 4

Fall back.
Spring forward.

In the fall we go back an hour.
In the spring, we go up an hour.