Hijri date in Vietnam

The difference in dates between countries

In fact, the date can be different between countries at the same time. This can happen when a country is in a time zone that is ahead or behind other countries.

This difference in time is due to the fact that the earth is divided into 24 time zones, and each time zone is offset from Coordinated Universal Time (UTC) by a certain number of hours. The time in each time zone is determined by the longitude of that location, with time zones to the east of the Prime Meridian (0° longitude) being ahead of UTC and time zones to the west being behind UTC.

So, while it may be a specific date and time in one location, it could be a different date and time in another location due to the difference in time zones.