The annual British change from BST British Summer Time to GMT Greenwich Mean Time, putting all our clocks back by one 1 hour at end of October

Daylight saving time (DST), also referred to as daylight savings time, daylight time (United States, Canada, and Australia), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks (typically by one hour) during warmer months so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in either the late winter or spring ("spring forward"), and to set clocks back by one hour in the fall ("fall back") to return to standard time. As a result, there is one 23-hour day in early spring and one 25-hour day in the middle of autumn. The idea of aligning waking hours to daylight hours to conserve candles was first proposed in 1784 by U.S. polymath Benjamin Franklin. In a satirical letter to the editor of The Journal of Paris, Franklin suggested that waking up earlier in the summer would economize on candle usage; and calculated considerable savings After synchronously resetting all clocks in a region to one hour ahead of standard time, individuals following a clock-based schedule will awaken an hour earlier than they would have otherwise—or rather an hour's worth of darkness earlier; they will begin and complete daily work routines an hour of daylight earlier: they will have available to them an extra hour of daylight after their workday activities. They will have one less hour of daylight at the start of the workday, making the policy less practical during winter. Proponents of daylight saving time argue that most people prefer a greater increase in daylight hours after the typical "nine to five" workday. Supporters have also argued that DST decreases energy consumption by reducing the need for lighting and heating, but the actual effect on overall energy use is heavily disputed