A Unix timestamp (also called epoch time) is the number of seconds elapsed since January 1, 1970 at 00:00:00 UTC. It is widely used in programming, databases, APIs, and log files as a universal way to represent a point in time.
It originated in early Unix operating systems in the 1970s as a simple, timezone-independent way to store time — just a single integer representing seconds since a fixed reference point (the "epoch").
On 32-bit systems, Unix time is stored as a signed 32-bit integer, which overflows on January 19, 2038. Modern 64-bit systems are not affected.