Time stamps generated by the system include the date and time. Time is often expressed in Coordinated Universal Time (UTC) — a modern continuation of Greenwich Mean Time (GMT) — or local time with an offset from UTC. The granularity of time measurements refers to the degree of synchronization between system clocks and reference clocks (e.g., clocks synchronizing within hundreds or tens of milliseconds). Organizations may define different time granularities for system components. Time service can be critical to other security capabilities (e.g., access control and identification and authentication), depending on the nature of the mechanisms used to support those capabilities.