What is Epoch / Unix Time?

Unix time (epoch time) is a way of representing a point in time as the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. It is timezone-independent and easy to compare or store.

Many systems use milliseconds instead of seconds. The classic 32-bit signed representation overflows in 2038 (the "Year 2038 problem"), which is why 64-bit timestamps are now standard.