NTP, the Network Time Protocol, is used to keep computer clocks accurate by synchronizing them over the Internet or a local network, or by following an accurate hardware receiver that interprets GPS, DCF-77, NIST or similar time signals.

sntp can be used as an SNTP client to query a NTP or SNTP server and either display the time or set the local system's time. It is not sufficient, however, for maintaining an accurate clock in the long run.