Daylight saving time

World map. Europe, most of North America, parts of southern South America, and southeastern Australia, and a few other places use DST. Most of equatorial Africa and a few other places near the equator have never used DST as the seasons are not marked by drastic changes in light. The rest of the landmass is marked as formerly using DST. — Daylight saving time regions:
  Northern Hemisphere summer

  Southern Hemisphere summer

  Formerly used daylight saving

  Never used daylight saving

Daylight saving time (DST), also referred to as daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to (in theory) make better use of the longer daylight available during summer by having darkness fall at a later clock time. The typical implementation of DST is to adjust clocks ahead of standard time by one hour in spring or late winter, and to set clocks back by one hour in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").

In many countries, the part of the year when DST is observed is much longer than the part aligned to standard time. The practice of DST was first tested and widely adopted in the early 20th century, since which many countries have abandoned DST partially or entirely.