Historically, these difficulties have always been a sore point of application developers’ efforts to create new applications. The implementation of Daylight Savings Time (DST) will be tough even if all of your users are in the same time zone (if the time zone supports DST). The reason for this is that within every single time zone, the distinction between 8:00 am on one day and 8:00 am on the next day would be 23 or 25 hours (depending on whether Daylight Saving Time began or ended overnight in between), rather than the usual 24 hours as it is in all other instances of the year.
It is vital for your application to have exact precision when storing and retrieving historical date and time information. In the system, there can be no ambiguity about the precise time an entry was made, irrespective of the local time zone or DST status at any tier, including the client (browser), the application (web service), and the database server.
As a result, there is widespread agreement that date/time values should always be stored in the database as UTC (coordinated universal time), which is a zero-offset number that never uses daylight saving time. Similarly, all date/time modification conducted by the application tier within the web service is done in Coordinated Universal Time (UTC). In the back end (from the IP geolocation API) endpoint through from the database persistence layer), by treating all date/time values as UTC, your application will reliably record the precise minute that an event happens, regarding the time zone or DST status at the different layers of the running program.
GMT — Coordinated Universal Time
The world is split into time zones, which each have its own difference in time. This offset is the number of minutes that must be added to the global time in order to determine the time zone of each country. In countries east of the Greenwich Meridian, local time is normally eight hours earlier than Greenwich Mean Time (GMT). For instance, local time in China is GMT +8 hours. In contrast, time is behind GMT west of the Greenwich Meridian, which means that local time is ahead of GMT.
Calculating the time zone is difficult
It might be difficult to determine the timezone for a given latitude and longitude. Even inside the United States/North America, this is a hugely problematic matter, particularly in areas bordering Mexico, such as the southwestern United States. You could drive for a few hours in just about any direction across Arizona and travel through eight distinct time zones, depending on when you are traveling. You always need an IP geolocation API to make sure about the correct time zone.
This, however, is not exclusive to the United States and the North American continent. See how other nations with similar longitudes, such as China and Russia, seem when seen in comparison. The People’s Republic of China has essentially removed time zones since 1949 and currently just has one time zone offset, UTC+0800. This covers the time zone range from UTC+0530 to UTC+0830, which used to be the case. Russia considers the longitudes UTC+0400 through UTC+0900 to be within the same range.
Timezone offsets can differ between latitudes and longitudes, across countries, and throughout seasons. However, to make matters worse, legislative changes are always occurring, which means that timezone offsets can be changed at any time. For example, in Russia, “On February 8, 2011, the Russian President signed a decree stating that Russia will observe Daylight Saving Time throughout the year.” According to the legislation, all clocks in Russia were advanced one hour on March 27, 2011, as was customary, but they were not to be changed back until October of the following year, essentially establishing Moscow Time UTC+4 indefinitely.