The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.
NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC).
It uses the intersection algorithm, a modified version of Marzullo’s algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions