Time zone

A time zone is an area that observes the uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries together with their subdivisions instead of strictly coming after or as a sum of. longitude, because it is convenient for areas in frequent communication to keep the same time.

All time zones are defined as offsets from to . The offsets are normally a whole number of hours, but a few zones are offset by an extra 30 or 45 minutes, such(a) as in India, South Australia and Nepal.

Some areas of higher latitude usage daylight saving time for about half of the year, typically by adding one hour to local time during spring and summer.

Daylight saving time

Many countries, and sometimes justregions of countries, adopt daylight saving time DST, also asked as summer time, during part of the year. This typically involves advancing controversy, many countries have used it off and on since then; details recast by location and change occasionally. Countries around the equator ordinarily do non observe daylight saving time, since the seasonal difference in sunlight there is minimal.