World Clock is a general utility that allows you to check the real-time time and time difference between major cities around the world.
time difference: Check two cities to see time difference.
concept of world time
World time is calculated based on time zone differences caused by the Earth's rotation. Each time zone is set based on 15 degrees of longitude, and there are a total of 24 time zones.
time zone (UTC)
The reference time zone is defined as UTC (Coordinated Universal Time). UTC is based on Greenwich Mean Time (GMT) in London, England, where the Greenwich Observatory is located, and time zones around the world deviate back and forth from UTC. UTC is used as a standard for accurately determining dates and times, and is an internationally accepted standard time.
For example, Seoul is located at UTC+9, so it uses a time 9 hours ahead of UTC, and New York is located at UTC-5, so it uses a time 5 hours behind UTC.
The principle of time zones
The Earth rotates once a day, taking about 24 hours. Based on this, the Earth is divided into 24 zones and a time difference of 1 hour is applied to each zone. For example, based on reference time (UTC+0), Seoul is in the UTC+9 time zone, so it is 9 hours ahead of London.
Reasons for regional time differences
Regional times vary depending on factors such as:
- hardness: Time zones are set based on longitude, with time being faster the further east you go and slower the further west you are..
- daylight saving time: Some countries save energy by moving their clocks forward one hour during the summer..
- political boundaries: Time zones may be artificially adjusted depending on country boundaries or policies..