The UNIX time function converts a date specification into UNIX time or a UNIX time into the corresponding date.
Unix time is a time definition developed for the operating system Unix and set as POSIX standard. Unix time counts the seconds elapsed since 00:00 UTC on Thursday, January 1, 1970. The start date is also referred to as The Epoch . The changeover from one second to the next is synchronous to UTC. Leap seconds are ignored, a leap second has the same time stamp as the second before it.
IMPORTANT: the conversion always starts from UTC. I.e. the local time should be converted to UTC accordingly. This means that the time zones or the summer/winter time have to be taken into account.