What Is System Time?

System time is one of the current times and dates that the computer system keeps track of so that applications running on the system have ready access to accurate time. Most computer systems base their system time on the current time in Greenwich, England, called the coordinated universal time (UTC). Each time zone is designated as being ahead or behind by a specific number of hours. Most computer system time settings are expressed in terms of Eastern Standard Time (EST), which is 5 hours ahead of Greenwich Mean Time (GMT), or Eastern Daylight Time (EDT), which is 4 hours ahead of GMT. In most cases, the computer system sets the system time automatically, but there may be instances where administrators want to manually set the system time for various reasons. One reason might be to synchronize the computer system's time with other systems or devices on the network. Another reason might be to reset the system time to a specific date and time, which could help troubleshoot issues with software or hardware that may be date sensitive. The system clock is based on the number of ticks that have occurred since an arbitrary starting date called the "epoch," usually the time from which first turned on the computer system or an agreed-upon specific date such as the Unix Epoch, which starts at the first of January 1970. In other words, if you're lucky enough to still have your computer from when you started it up for the first time (or if you're just old), you'll know what time it was when your computer first turned on. During that first startup of your computer, the current system time was set to an epoch date and then moved on from there. Depending on your system, either its correct time will automatically sync with UTC on the Internet, or you'll have to set it by yourself manually.