standard time
Sign in to savesynchronization of clocks within a geographical area or region
Article
Worldwide time zones at present
Standard time is the synchronisation of clocks within a geographical region to a single time standard, rather than a local mean time standard. The term is also used to contrast with daylight saving time, a period of the year when clocks are shifted ahead one hour, supposedly to make better use of daily sunlight from spring to fall. Applied globally in the 20th century, the geographical regions became time zones. The standard time in each time zone has come to be defined as an offset from Universal Time. A further offset is applied for part of the year in regions with daylight saving time. Generally, standard time agrees with the local mean time at some meridian that passes through the region, often near the centre of the region. Historically, standard time was established during the 19th century to aid weather forecasting and train travel.