Unix timestamp
The number of seconds elapsed since 1 January 1970 UTC.
A Unix timestamp (or epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. It is a compact, time-zone-independent way for computers to store and compare moments in time. Many systems also use milliseconds. The value is universal: the same instant has the same timestamp everywhere on Earth.
Example: 1700000000 corresponds to 14 November 2023, 22:13:20 UTC.