Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks developed back in 1985.
NTP provides Coordinated Universal Time (UTC) including scheduled leap second adjustments. No information about time zones or daylight saving time is transmitted; this information is outside its scope and must be obtained separately.
It is usually able to maintain time to within tens of milliseconds over the public Internet and can achieve 1 millisecond accuracy on local area networks under ideal conditions.
The current reference implementation is version 4 (NTPv4), which is a proposed standard as documented in RFC 5905. It succeeds version 3, specified in RFC 1305.
