Current Unix time ()
Unix time is a date and time representation widely used in computing. It measures time by the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the Unix epoch, without adjustments made due to leap seconds. In modern computing, values are sometimes stored with higher granularity, such as microseconds or nanoseconds.
Unix time originated as the system time of Unix operating systems. It has come to be widely used in other computer operating systems, , programming languages, and databases.
Unix time is currently defined as the number of seconds which have passed since 00:00:00 UTC on Thursday, 1 January 1970, which is referred to as the Unix epoch. Unix time is typically encoded as a signed integer.
The Unix time 0 is exactly midnight UTC on 1 January 1970, with Unix time incrementing by 1 for every non-leap second after this. For example, 00:00:00 UTC on 1 January 1971 is represented in Unix time as 31536000. Negative values indicate times before the Unix epoch, with the value decreasing by 1 for every non-leap second before the epoch. For example, 00:00:00 UTC on 1 January 1969 is represented in Unix time as -31536000. Every day in Unix time consists of exactly 86400 seconds.
Unix time is sometimes referred to as Epoch time. This can be misleading since Unix time is not the only time system based on an epoch and the Unix epoch is not the only epoch used by other time systems.
Unix time differs from both Coordinated Universal Time (UTC) and International Atomic Time (TAI) in its handling of leap seconds. UTC includes leap seconds that adjust for the discrepancy between precise time, as measured by atomic clocks, and solar time, relating to the position of the earth in relation to the sun. International Atomic Time (TAI), in which every day is precisely 86400 seconds long, ignores solar time and gradually loses synchronization with the Earth's rotation at a rate of roughly one second per year. In Unix time, every day contains exactly 86400 seconds.