The basic timekeeping standard for almost all of the world's local time zones is called Coordinated Universal Time (UTC). UTC is derived from International Atomic Time (TAI) and Universal Time (UT1), also known as mean solar time because it’s the time it takes for the Earth to rotate once on its axis. Because the rotation of the earth varies a bit over time and is slowly decreasing its mean rotation speed, a deviation occurs between UTC and UT1. When this deviation approached .9 seconds, a leap...
