Time zone

A region that observes the same standard time, usually defined by its offset from Coordinated Universal Time and seasonal clock rules.

Coordinated Universal Time: The primary time standard by which clocks and time are regulated worldwide. Time-zone offsets specify local time relative to this global standard.
Local mean time: A time standard based on the mean solar time at a particular longitude. Before zones, towns commonly set clocks by their own local mean time.
Unix time: A system that represents time as seconds elapsed from a defined epoch, usually excluding leap seconds. Computers often store instants independently of local zone display rules.
Solar time: A time system based on the apparent or mean position of the Sun in the sky. Its continuous variation with longitude differs from shared regional clock time.
UTC offset: The difference in hours and minutes between a local time and Coordinated Universal Time. An offset is the basic numerical rule used to define standard time.
Railway time: A standardized timetable time adopted by railway companies to coordinate trains across localities. Railways needed shared clock standards across places with different local times.
Cron: A time-based job scheduler used on Unix-like operating systems. Scheduled jobs must account for local clock changes and zone settings.
Decimal time: A timekeeping system that divides the day into units based on powers of ten. It proposes a different organization of clock time, rather than regional offsets.
Daylight saving time: The seasonal practice of advancing clocks to extend evening daylight by the clock. Some zones change their UTC offset seasonally under this rule.
Sandford Fleming: A Canadian railway engineer who promoted a worldwide system of standard time zones. His proposals helped popularize dividing the globe into hourly time zones.

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