Summary: Time and date management are complicated and nasty on computers, because they are complicated and nasty in real life. While we often think of being able to tell time as being simple, historically it hasn't been. We're continually having to work to keep our timekeeping devices accurate so that we can use their results for everything from manufacturing to navigation, encryption, and missile guidance. Network Time Protocol (NTP) is used to synchronize time over packet-switched, variable-latency data networks. The goal is to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC).
