Fortunately it is easy to keep your clock in sync without manually fiddling with the clock. The Network Time Protocol (NTP) is a protocol that enables a computer to get its time from a remote server and to be accurate within milliseconds even if the network is unreliable. Coupled with NTP is a globally distributed network of freely usable servers that participate in the protocol.
Throughout the world are various clock sources, such as government agencies broadcasting the time over radio, high-quality cesium clocks, or devices that read the current time from satellites. These clocks are called reference clocks in the NTP system.