> The time used for "Unix Time" is actually UTC Unix Time is not UTC; it is a linear representation that is surjective onto UTC. It is easy to map between the

> The time used for "Unix Time" is actually UTC Unix Time is not UTC; it is a linear representation that is surjective onto UTC. It is easy to map between the two but they are not the same. They are not even isomorphic or bijective because leap seconds have no unique representation in Unix Time. The Unix Time representation gives up full equivalence with UTC in order to provide some useful guarantees (days are always exactly 86,400 seconds long, midnight always satisfies x % 86,400 == 0, etc), but also creates other surprises (time can go backwards when a leap second occurs).