Timezone or standard time is also called as regional time. This Greenwich mean time (Greenwich mean time is a local clock time at Greenwich) was decided on 13 October 1884. And the time of the whole world’s clock is decided according to this timezone.
Working of Timezone
Before 18th century in the whole world sun clock is used to watch the time. But Sir Standford Fleming made a timezone from which world gets the right direction of time.
When the sun arises it can stay only one side of the earth.
That’s why at some places of the earth get a straight beam of light of the sun ,
and the other places of the earth get a slanting beam of light of the sun.

Because of this reason, there is the day in some places of earth or the evening at the other places of the earth.
If the world’s clock set to the same time it makes a big problem.
Because of this reason, some places have a day and some places have an evening at the same time as 5 o’clock.
To solve this problem standard time is comes in picture.
The map of whole world divided according to longitude lines by the distance of 15 degree by the 24 equal imaginary parts and it is start from 0 degree.
This 0-degree line starts from Greenwich of England which is situated in vedhshala. Counting time starts from here. This time is also known as international Greenwich meantime. The right side from the Greenwich line’s country time is forward and the left side from the Greenwich line’s country time is backward.
Timezone :

In the same way, every country has its own standard time. In India, this line is passes over Naini village near Allahabad, from here the standard time of India gets decided.
India’s standard time is located at the right side from the Greenwich line at 82.5 degrees, this means the Greenwich time of India is forward by the time of 5 hours.means when in the Greenwich time will be 12 o’clock of night than in India time will be the 5:30 AM of the morning.