Time zones around the world are exp

Time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset.

The westernmost time zone uses UTC−12, being twelve hours behind UTC; the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the island nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day.

UTC is used in many Internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the Internet, encodes times using the UTC system.[10] Computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official Internet UTC servers. For sub-microsecond precision, clients can obtain the time from satellite signals.

UTC is also the time standard used in aviation,[11] e.g. for flight plans and air traffic control clearances. Weather forecasts and maps all use UTC to avoid confusion about time zones and daylight saving time. The International Space Station also uses UTC as a time standard.

Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many timezones.[12]

UTC is also used in digital tachographs used on large goods vehicles (LGV) under EU and AETR rules.