Coordinated universal time (UTC) is a time scale that is kept by time laboratories around the world and is determined by using highly precise atomic clocks. The UTC time is accurate to approximately a nanosecond (billionth of a second) per day. UTC is located at 0 degrees latitude, the Prime Meridian.
UTC is used as the starting point to calculate the system time. To calculate the system time from UTC, the system's offset from UTC is added to UTC. The offset specifies the number of hours and minutes that the system is either west or east of UTC. Everything west of the Prime Meridian has a negative offset and everything east has a positive offset. Then, the offset is applied to UTC to calculate the system time. The system time is displayed in the time of day system value.
The following figure shows where UTC is located relative to Server A. UTC has a time value of 4:00 p.m. Server A is located in the United States of America in the Central Standard Time zone. Server A is located west of UTC 6 hours; therefore, Server A is offset from UTC by -06:00 hours. To calculate Server A's system time, add a negative 6 hours (-06:00) to 4:00 p.m., which is the current time value for UTC. With this calculation, Server A's local system time is 10:00 a.m.
