'''समय क्षेत्र''' संसारको त्यस्तो क्षेत्र हो जहाँ एउटै [[समय]] अपनाइएको हुन्छ । यसलाई '''स्थानीय समय''' पनि भन्ने गरिन्छ । धेरैजसो एक आपसमा जोडिएका समय क्षेत्रहरूमा एक घण्टाको फरक हुन्छ र सामान्यतया [[ग्रेनिच]] समयका आधारमा निर्धारण गरिन्छ । (see also [[Coordinated Universal Time|UTC]]). ▼
▲'''समय क्षेत्र''' संसारको त्यस्तो क्षेत्र हो जहाँ एउटै [[समय]] अपनाइएको हुन्छ । यसलाई '''स्थानीय समय''' पनि भन्ने गरिन्छ । धेरैजसो एक आपसमा जोडिएका समय क्षेत्रहरूमा एक घण्टाको फरक हुन्छ र सामान्यतया [[ग्रेनिच]] समयका आधारमा निर्धारण गरिन्छ । (see also [[Coordinated Universal Time|UTC]]).
[[Image:Standard time zones of the world.png|thumb|400px|Standard Time Zones of the World as September 2011]]▼
▲[[Image:Standard time zones of the world.png|thumb|400px|Standardविश्वको Timeकानक Zonesसमय of२०११ theको World as September 2011अनुसार]]
Standard time zones can be defined by geometrically subdividing the Earth's [[spheroid]] into २४ [[lune]]s (wedge-shaped sections), bordered by [[meridians]] each १५° of [[longitude]] apart. The local time in neighbouring zones would differ by one hour. However, political र geographical practicalities can result in irregularly-shaped zones that follow political boundaries or that change their time seasonally (as with [[daylight saving time]]), as well as being subject to occasional redefinition as political conditions change.
There are variations of the definitions of ''time zone'' which generally fall into two meanings: a समय क्षेत्र can represent a region where the local time is some fixed offset from a global reference (usually UTC), or a समय क्षेत्र can represent a region throughout which the local time is always consistent even though the offset may fluctuate seasonally.
Before the adoption of time zones, people used local [[solar time]] (originally ''apparent'' solar time, as with a [[sundial]]; and, later, ''mean'' solar time). Mean solar time is the average over a year of apparent solar time. Its difference from apparent solar time is the [[equation of time]].
This became increasingly awkward as [[rail transport|railways]] र [[telecommunication]]s improved, because clocks differed between places by an amount corresponding to the difference in their geographical longitude, which was usually not a convenient number. This problem could be solved by synchronizing the clocks in all localities, but then in many places the local time would differ markedly from the solar time to which people are accustomed. Time zones are thus a compromise, relaxing the complex geographic dependence while still allowing local time to approximate the mean solar time. There has been a general trend to push the boundaries of time zones further west of their designated meridians in order to create a permanent daylight saving time effect. The increase in worldwide communication has further increased the need for interacting parties to communicate mutually comprehensible time references to one another.
