Whenever if you need to make an International long distance phone call, or if you're planning a trip to a foreign destination, even if you are preparing an online meeting, you need accurate information about the Exact Time on the specific region of the world you are interested, or if you need to contact someone in somewhere at specific time.

Time is currently one of the few fundamental quantities. These are quantities which cannot be defined via other quantities because there is nothing more fundamental than what is presently known. Thus, similar to definition of other fundamental quantities (like space and mass), time is defined via measurement. This is the only definition of time in science. Wikipedia

World Buddy - The Exact Time in any of the world's time zones. Daylight savings time is included in the conversion when appropriate, and the zones are kept abreast of political changes. www.worldbuddy.com

The official U.S. Time - The official Exact Time in the U.S. www.time.gov

Date Heure - Current date time in all timezones and major cities. All on one page. www.date-heure.com

Clock Link - Provides fashionable clocks that you can easily embed in your web page. www.clocklink.com

Time and Date - Check the Exact Time around the World. www.timeanddate.com

Digital clock

There are a large variety of devices that have been invented to measure the Exact Time. The study of these devices is called horology. A sundial uses a gnomon to cast a shadow on a set of markings which were calibrated to the hour. The position of the shadow marked the hour in local time. An hourglass uses the flow of sand to measure the flow of time. In the ancient World, the most accurate timekeeping device were the waterclock or "clepsydra", first found in Egypt.

Today, the most common devices for periods less than a day are the clocks, and the calendar, for periods longer than a day. Clocks can range from watches, to more exotic varieties such as the Clock of the Long Now. They can be driven by a variety of means, including gravity, springs, and various forms of electrical power, and regulated by a variety of means such as a pendulum. There are also a variety of different calendars, for example the Lunar calendar and the Solar calendar, although the Gregorian calendar is the most commonly used.