Epoch:
Epoch means an instant in time chosen as the origin of a particular era, it serves as a reference point from which time is measured.
The Unix epoch is the time 00:00:00 UTC on January 1, 1970.
TZ:
Time Zones are a geographical world globe division of 15 degree each (So 24 time zones exist in the world), starting at Greenwich, in England, created to help people know what time is it now in another part of the world.
UTC:
Coordinated Universal Time is a time standard based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the Earth's slowing rotation. Leap seconds are used to allow UTC to closely track UT1, which is mean solar time at the Royal Observatory, The difference between UTC and UT1 cannot exceed 0.9 seconds, so if high precision is not required the general term Universal Time (UT) (without a suffix) may be used. Greenwich.
UTC uses a 24-hour system of time notation. "1:00 a.m." in UTC is expressed as 0100, pronounced "zero one hundred." Fifteen minutes after 0100 is expressed as 0115; thirty-eight minutes after 0100 is 0138 (usually pronounced "zero one thirty-eight"). The time one minute after 0159 is 0200. The time one minute after 1259 is 1300 (pronounced "thirteen hundred"). This continues until 2359. One minute later is 0000 ("zero hundred"), and the start of a new UTC day.
GMT
Greenwich Mean Time was based upon the time at the zero degree meridian that crossed through Greenwich, England. GMT became a world time and date standard because it was used by Britain's Royal Navy and merchant fleet during the nineteenth century.
Today, UTC uses precise atomic clocks, shortwave time signals, and satellites to ensure that UTC remains a reliable, accurate standard for scientific and navigational purposes. Despite the improvements in accuracy, however, the same principles used in GMT have been carried over into UTC.
LT
Local time depends on local time zone. To convert UTC to local time, you have to add or subtract hours from it. For persons west of the zero degree meridian to the international date line, offser hours are subtracted from UTC to convert to local time; For persons east of the zero degree meridian to the international date line, offser hours are added to UTC to convert to local time;
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