Let's talk about time zones. So do we ever think why is time zone different for different countries, what are the factors that makes time zone different in different regions or countries. Why it is not same across the globe. OK, don't get confused you will get all your answers in this article.
A time zone is a region or an area in our earth which has same time for all places in that region. Earth is divided into 24 region according to time zones. In one time zone area time will be same for each place in that area.
Time zone is determined by the longtitude (in degrees) of a area. Dividing the logtitude by 15 will give the accurate time zone of that area. For example lontitude of an area is 45 degree East then timezone will be 45/15 = +3 i.e. GMT+3.00 or UTC+3.00. If the longtitude is 45 degree west then time zone will be -(45/15) = -3 i.e. GMT-3.00 or UTC -3.00. Now another question comes that what is longtitude and how it is determined.
Longtitude: Latitude is a geographical coordinate which determines the east west position of a point in earth surface.
Latitude: Latitude is a geographical coordinate which determines the north south position or a point in earth surface.
So as we have seen time zone depends on longtitude of a specific area. However different countries are free to determine time zones in their country.