Time zones are using for adjusting the time coordinately for the world. It’s using for commercial, legal and social situations. Coordinated Universal Time is known as UTC and its time period is UTC−12 to UTC+14. Some countries need daylight saving time to adjust hours to UTC every year. Time zone need started on 19th century. Clocks were spreading fast but there were no coordination in cities or areas. Every city of England was using different time zones. Greenwich Mean Time was working still 1675 but its main mission was showing the longitude to English Seaman. After trains and cars are started to work widely in 19th century, time zones became a must. How many time zones are there in the world?
Today there are 39 time zones in the world. Firstly Quirico Filopanti wrote the idea of 24 hours day in his book. He offered to use meridians for time zones.
Greenwich Mean Time was using as time zone designator. After 1972 UTC started to broadcast radio signals for time. Greenwich Mean Time is now the starting point of time zones with its longitude 0°. It’s also known as Prime Meridian.
Symbolically time zone starts with UTC−12:00 on Baker Island, UTC−11:00 is American Samoa, UTC−10:00 is Hawaii. UTC−07:00 is Canada. UTC−05:00 is Colombia. UTC−04:00 is Brazil. UTC−03:00 is Argentina. UTC+03:00 is Iraq. UTC+07:00 is Vietnam. UTC+09:30 is Australia. UTC+12:00 is New Zealand. There are also works for using the time zones in space.