Question

How is the standard time of a place determined? 

Answer 1

1. The local time at the longitude which generally passes through the middle of the country is deemed to be the standard time for that country. This standard time is used all over the country.
2. Normally, if the difference between the longitudinal extent of the country is less than one or two hours, only one standard time is considered for the country.
3. But if the longitudinal extent (east-west extent) is more than that, then, one standard time is not enough and in such countries, more than one standard time zones are considered. For example, Canada has 6 time zones.