A time zone is a region of the globe that observes a uniform standard time for legal, commercial, and social purposes. Time zones tend to follow the boundaries of countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in close commercial or other communication to keep the same time.
Most of the time zones on land are offset from Coordinated Universal Time (UTC) by a whole number of hours (UTC−12:00 to UTC+14:00), but a few zones are offset by 30 or 45 minutes (e.g. Newfoundland Standard Time is UTC−03:30, Nepal Standard Time is UTC+05:45, Indian Standard Time is UTC+05:30 and Myanmar Standard Time is UTC+06:30). (https://en.wikipedia.org/wiki/Time_zone)
Timezone Maps of the World
World Time Zones Map
Standard time zones of the world:Maps in the Library of Congress, 2006 maps
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World – time zones map (2014)
1866 Johnson Chart of World Time Zones, from Washington
World Time Zone Chart 1942
Timezone Map UTC+545 (Nepal)