time_t

From cppreference.com
< c | chrono
Defined in header <time.h>
typedef /* unspecified */ time_t;

Arithmetic type capable of representing times.

Although not defined, this is almost always a integral value holding the number of seconds since 00:00, Jan 1 1970 UTC, corresponding to POSIX time.

[edit] See also

returns the current time of the system as time since epoch
(function)
converts time since epoch to calendar time expressed as local time
(function)
converts time since epoch to calendar time expressed as Universal Coordinated Time
(function)