std::time_t - cppreference.com

From cppreference.com

typedef /* unspecified */ time_t;

Arithmetic type capable of representing times.

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

See also

returns the current time of the system as time since epoch
(function) [edit]
converts time since epoch to calendar time expressed as local time
(function) [edit]
converts time since epoch to calendar time expressed as Universal Coordinated Time
(function) [edit]
converts a system clock time point to std::time_t
(public static member function of std::chrono::system_clock) [edit]