Meaning – The term epoch, also known as epoch time, is the starting point of an operating system, that is determined by the tick count from the epoch.

Epoch is also referred to as the time and date corresponding to 0 in an operating systemís clock and time-stamp values. For most versions of the UNIX operating system, the epoch is 00:00:00 GMT, 01 January 1970. System time is measured as the number of seconds past the epoch.

The reason that an epoch value is used by the computer is that converting a date and time into an epoch value makes it easier to find the difference, add, and subtract from a time value.

Example of usage “Unix and POSIX measure time as the number of seconds that have passed since 1 January 1970 00:00:00 UT, a point in time known as the Unix epoch.”