World Timezone Clock
WorldClock.com provides accurate world time, statistics and weather in major cities across the world. With incomparable time-telling precision, World Timezone Clock is the perfect point of reference for travelers and business people alike. Whether you’re looking to book a flight, schedule an international teleconference, use our time zone converter or our time zone map and observe the trading hours of an overseas business, World Timezone Clock can show you the time in a matter of seconds. There are two standards by which a country’s time zone is categorized; the older of the two standards is Greenwich Mean Time (GMT) and the more modern of the two standards is Coordinated Universal Time (UTC). However, there is no actual time difference between GMT and UTC and therefore the two can be used interchangeably. Time zones are regions of the earth divided by lines of longitude. There are 24 different time zones on earth to correlate with the 24 hours in each day and which are displayed in our time zone map here at World Clock. The UK sets the standard for Greenwich Mean Time at “GMT 0” and other countries can calculate their time zone in accordance with how many hours they are ahead of or behind the UK. For instance, Saudi Arabia, which is 3 hours ahead of the UK, has a time zone of “GMT +3” and Colombia, which is 5 hours behind the UK, has a time zone of “GMT -5”. Daylight Savings Time (DST) is practiced in certain parts of the world in order to allow for more hours of daylight during the working day. Therefore, for half of the year some countries adjust their clocks by one hour. World Clocks are adjusted forward by one hour in the early spring and then set back by one hour in the autumn. This means that, in the spring, a clock will go from 4:00 Standard Time to 5:00 DST.
The first known person to conceive of a worldwide system of time zones was the Italian mathematician Quirico Filopanti. He introduced the idea in his book Miranda! published in 1858. He proposed 24 hourly time zones, which he called "longitudinal days", the first centred on the meridian of Rome. He also proposed a universal time to be used in astronomy and telegraphy. But his book attracted no attention until long after his death.
Scottish-born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in 1879. He advocated his system at several international conferences, and is credited with "the initial effort that led to the adoption of the present time meridians". In 1876, his first proposal was for a global 24-hour clock, conceptually located at the centre of the Earth and not linked to any surface meridian. In 1879 he specified that his universal day would begin at the anti-meridian of Greenwich (180th meridian), while conceding that hourly time zones might have some limited local use. He also proposed his system at the International Meridian Conference in October 1884, but it did not adopt his time zones because they were not within its purview. The conference did adopt a universal day of 24 hours beginning at Greenwich midnight, but specified that it "shall not interfere with the use of local or standard time where desirable".