World clock - Current local time and date in major cities around the world
What's the time now?
We can quickly get our local time now, however, as you would like to make an international long-distance phone call, or have a international online meeting, or plan to have a vacation to a foreign country, first of all, you should know the current local time now. You can quickly find out the accurate time around the world by the website of localtimenow.com.
World time zones & Time difference
The time of earth is divided into 24 time zones with 15 degrees of longitude in width. In fact, the time zone is a region that has a uniform standard time for commercial, legal and social purposes. It is not strictly divided by a straight line from north to south, but by the natural conditions to divide, such as a country astride two or more time zones, in order to take care of administrative convenience, the country may in the same time zone or the neighboring time zones. Time zones around the world are expressed as negative or positive offsets from UTC, as in the list of time zones by UTC offset.
Time difference is definition as the difference in standard time between places in different time zones. When you would like to fly two or more time zones, that may mean you should adjust your sleeping. For example: flying from New York to Tokyo, that leaves you with a 13-hour difference, that effectively means reversing your sleep/wake schedule.
Official time
In fact, many countries and regions of the world are not strictly use time zones to calculate the time. They often use time of one time zone as their nationwide uniform time, that is official time. For example, China geographically spans five time zones, the official time in China follows a single standard time of UTC+08:00 which is 8 hours ahead of Greenwich Mean Time. As another example, in France, the Netherlands and Belgium, although located in the middle time zone, they use the time of UTC+01:00 as their official time, in order to be consistent with most European countries.
Daylight savings time
Daylight saving time (abbreviated: DST) is an energy-saving system where artificially prescribed time. It is the practice of advancing clocks during the lighter months so that evenings have more apparent daylight and mornings have less. It is also called as Summer Time in the United Kingdom. Usually the clocks are adjusted forward one hour near the start of spring, and are adjusted backward one hour in the autumn. The specific provisions of daylight saving time varies from country. Currently there are nearly 110 countries implement the daylight saving time in the worldwide.
Coordinated Universal Time & Greenwich Mean Time
Coordinated Universal Time (French: Temps Universel Coordonné), abbreviated as UTC, is the primary time standard by that the world regulates clocks and time. Generally, UTC is synonymous with Greenwich Mean Time (GMT), but GMT is no longer precisely defined by the scientific community. The UTC was officially formalized in 1963, and its current version is defined by International Telecommunications Union Recommendation (ITU-R TF.460-6). UTC is the time standard used for many Internet and World Wide Web standards, is also the time standard used in aviation.
Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London, adopted starting with British railroads in 1847. And later it became adopted as a global time standard. Before 1 January 1972, GMT was same as Universal Time (UT), a standard astronomical concept used in many technical fields. Since the introduction of UTC in 1972, the term "GMT" was no longer used in astronomers. In the United Kingdom, GMT is the official time during winter; during summer British Summer Time (BST) is used. GMT is the same as Western European Time. Sometimes, the term "Greenwich Mean Time (GMT) is used informally to refer to UTC.