Summer time

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Daylight saving time is the time usually presented by one hour compared to the zone time, which serves as legal time during a certain period in the summer half-year (and often a little beyond). Such a scheme is applied almost only in temperate countries.
Central European summer time begins on the last Sunday in March at 2:00 CET, presenting the hour count at one hour from 2:00 to 3:00. It ends on the last Sunday in October at 3:00 CEST by resetting the hour count by one hour from 3:00 to 2:00.

Basic principles
From ancient times, the local solar time, which is defined by the hour angle of the sun, served as a time system for everyday use. So it is at noon (time of the highest sun position) 12:00 clock and at midnight 0:00 clock. In order to eliminate the location dependence of time – a geographical longitude difference of one degree corresponds to a time difference of 4 minutes – within a country, a global system of 24 time zones with an east-west extension of approximately 15° geographical longitude difference was created at the 1884 International Meridian Conference, starting from the Greenwich zero meridian. Each time zone was assigned a zone time which (by the definition at that time) was equal to the mean solar time of the meridian of the zone with the geographical lengths 0°, 15°, 30° ... east and west of Greenwich. The zone times of two neighboring zones differ by exactly one hour. A zone time is uniform and uniform within the countries of the same time zone. In compliance with these conditions, it deviates as little as possible from the local solar time. The difference between the local solar time and the zone time of a place is negative east of the median meridian and positive west of it, and if the boundaries of the time zones coincide approximately with their natural position – which is often no longer true today – the amount of this difference in the annual average is nowhere significantly greater than half an hour.

The legal times of each country are defined as the zone time of the time zone to which the country belongs according to its geographical length. Thus, Central European Time (CET) is the zone time in the Central European Time Zone with the reference meridian of the geographical length 15° East. It thus differs from the Greenwich zero meridian Coordinated Universal Time UTC by 1 hour: CET = UTC + 1 hour.

Due to economic and political considerations, in many countries a summer time preceding this normal legal time by one hour was repeatedly introduced as legal time for limited periods in the summer half-year. The summer time is thus equal to the zone time of the eastern neighboring time zone, i.e. approximately the Central European Summer Time (CEST) =