AEDT

Australia uses three main time zones: Australian Western Standard Time (AWST; UTC+08:00), Australian Central Standard Time (ACST; UTC+09:30), and Australian Eastern Standard Time (AEST; UTC+10:00). Time is regulated by the individual state governments, some of which observe daylight saving time (DST). Australia's external territories observe different time zones.

Standard time was introduced in the 1890s when all of the Dominions adopted it. Before the switch to standard time zones, each local city or town was free to determine its local time, called local mean time. Now, Western Australia uses Western Standard Time; South Australia and the Northern Territory use Central Standard Time; while New South Wales, Queensland, Tasmania, Victoria, and the Australian Capital Territory (ACT) use Eastern Standard Time.

Daylight saving time is used in South Australia, New South Wales, Victoria, Tasmania, and the ACT. It is not currently used in Western Australia, Queensland or the Northern Territory.

The standardization of time in Australia began in 1892, when surveyors from the six Dominions in Australia met in Melbourne for the Intercolonial Conference of Surveyors. The delegates accepted the recommendation of the 1884 International Meridian Conference to adopt Greenwich Mean Time (GMT) as the basis for standard time.

The Dominions enacted time zone legislation, which took effect in February 1895. The clocks were set ahead of GMT by eight hours in Western Australia; by nine hours in South Australia (and the Northern Territory, which it governed); and by 10 hours in Queensland, New South Wales, the Dominion of Victoria and Tasmania. The three time zones became known as Eastern Standard Time, Central Standard Time, and Western Standard Time. Broken Hill in the far west of New South Wales also adopted Central Standard Time due to it being connected by rail to Adelaide but not Sydney at the time.

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Wikipedia