Unix time (also known as Epoch time, POSIX time, seconds since the Epoch, or UNIX Epoch time) is a system for describing a point in time. It is the number of seconds that have elapsed since 1st January 1970, minus leap seconds. Leap seconds are ignored, with a leap second having the same Unix time as the second before it, and every day is considered as if it contains exactly 86400 seconds.
The epoch is Unix time 0 (midnight 1/1/1970), but 'epoch' is used as a synonym for Unix time. Some systems store epoch dates as a signed 32-bit integer, which might cause problems on January 19, 2038 (known as the Year 2038 problem or Y2038). The converter on this page converts timestamps in seconds (10-digit), milliseconds (13-digit) and microseconds (16-digit) to readable dates.