Daylight saving time

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 make better use of the longer daylight available during summer so that darkness falls 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.