Switzerland uses Central European Time (CET) during the winter as standard time, which is one hour ahead of Coordinated Universal Time (UTC+01:00), and Central European Summer Time (CEST) during the summer as daylight saving time, which is two hours ahead of Coordinated Universal Time (UTC+02:00).^[1]

The electrical telegraph was introduced in Switzerland in 1851, which allowed near real-time communication, especially amongst post offices. By July 1853, all telegraph and post offices across Switzerland were using Bernese time,^[2] a local mean time measured from the Zytglogge clocktower^[3] at UTC+00:29:45.5.^{[lower-alpha 1]} Bernese time was also used on train timetables by at least 1873.^[5] On 1 June 1894, UTC+01:00 was officially adopted nationwide.^[6] Daylight saving time was first attempted between 1941 and 1942, by moving the clocks forward one hour at 01:00 on the first Monday in May, and back again at 02:00 on the first Monday in October.^{[citation needed]} The decision to observe daylight saving time was made by the Federal Council on behalf of the recommendation of the Federal Chancellery.^[7]

Whilst DST was introduced in much of Western Europe in the spring of 1980, Switzerland did not implement DST until the following year. This resulted in there being a one hour time difference between Switzerland and most of Western Europe, including all of the bordering countries (with the exception of Liechtenstein) for around six months in 1980.^{[citation needed]}

The German village of Büsingen am Hochrhein, a small exclave, entirely surrounded by Swiss territory, did not implement DST in 1980 either and observed the same time as Switzerland, meaning there was a one hour time difference between this village and the rest of Germany. The zone Europe/Busingen was created in the 2013a release of the tz database,^[8] because since the Unix time epoch in 1970, Büsingen has shared clocks with Zurich.^[9]

Since 1981 the shifts to DST occur on the date as specified for European Summer Time.^{[citation needed]}

The difference of longitude between the western and easternmost points of Switzerland is equivalent to 4°32′09″, resulting in a difference of approximately 18 minutes of solar time.^{[citation needed]}

The IANA time zone database contains one zone for Switzerland in the file zone.tab, named Europe/Zurich. Columns marked with * are the columns from zone.tab itself.^{[citation needed]}

Computers not supporting "Europe/Zurich" may use the older POSIX syntax: TZ='CET-1CEST,M3.5.0/2,M10.5.0/3'^{[citation needed]}