Daylight saving time

Clocks are advanced by one hour during the very early morning at the beginning of DST.

When DST ends, clocks are set back (as if to repeat one hour) during the very early morning. Specific times vary.

Daylight saving time (DST) or summer time (ST) is a time to keep during summer. During the summer months, the sun stays visible for a longer time, and sunset happens late in the day. For this reason, certain countries advance the time by one hour near the start of summer, and put it back one hour during autumn.

DST helps stores that sell to people after they get off work, and it doesn't hurt farmers and others whose hours are set by the sun. It cuts traffic accident rates. Sometimes it can reduce energy costs, but it can also increase them.

Most of the world's countries do not use DST, but it is common in Europe and North America.

The United States, Australia, the United Kingdom, Canada and many other countries have DST. These countries also have regions that do not have DST:

• United States: most of Arizona and Hawaii
• Australia: Queensland, Western Australia and the Northern Territory
• Canada: Saskatchewan except for a few locations with the border with Alberta and Manitoba, and the Yukon Territory

Iceland, Russia, Belarus, and some parts of Ukraine are countries in Europe without DST.