Australia is divided into three separate time zones:
Australian Eastern Standard Time (AEST) covers the eastern states of Queensland, New South Wales, Victoria, Tasmania and the Australian Capital Territory. AEST is equal to Coordinated Universal Time plus 10 hours (UTC +10).
Australian Central Standard Time (ACST) covers the state of South Australia, the town of Broken Hill in western New South Wales and the Northern Territory. ACST is equal to Coordinated Universal Time plus 9½ hours (UTC +9½).
Australian Western Standard Time (AWST) covers Western Australia. AWST is equal to Coordinated Universal Time plus 8 hours (UTC +8).
In summer, New South Wales, Victoria, South Australia, Tasmania and the ACT turn their clocks forward one hour to Daylight Saving Time (DST). Daylight Saving Time begins at 2:00am (AEST) on the first Sunday in October and ends at 3:00am (Australian Eastern Daylight Time) on the first Sunday in April.
NSW, ACT, Victoria and Tasmania move from AEST to Australian Eastern Daylight Time (AEDT), UTC +11. South Australia and the NSW town of Broken Hill move from ACST to Australian Central Daylight Time (ACDT), UTC +10½.
Daylight saving is not observed in Queensland, the Northern Territory or Western Australia.
Greenwich Mean Time (GMT) is zero degrees longitude and the world’s time zones are measured east or west of this line. The term Coordinated Universal Time (UTC) is now widely used instead.
The International Date Line crossing the Pacific Ocean changes the date by one day. If you cross the date line moving east, you subtract a day; if travelling west you add on a day (with local variations). Travelling direct from Los Angeles or London to Australia you arrive two days later; travelling back, you arrive the same day you departed. That is, if you ever want to leave.