national standardsCoordinated Universal TimeoffsetUTΔTDUT1International Earth Rotation and Reference Systems ServiceISO 31-1ISO 8601International Atomic Time12-hour clock24-hour clockBarycentric Coordinate TimeBarycentric Dynamical TimeCivil timeDaylight saving timeGeocentric Coordinate TimeInternational Date LineIERS Reference MeridianLeap secondSolar timeTerrestrial TimeTime zone180th meridianObsolete standardsEphemeris timeGreenwich Mean TimePrime meridianTime in physicsAbsolute space and timeSpacetimeChrononContinuous signalCoordinate timeCosmological decadeDiscrete time and continuous timeProper timeTheory of relativityTime dilationGravitational time dilationTime domainTime translation symmetryT-symmetryHorologyClockAstrariumAtomic clockComplicationHistory of timekeeping devicesHourglassMarine chronometerMarine sandglassRadio clockWatchstopwatchWater clockSundialDialing scalesEquation of timeHistory of sundialsSundial mar