A Temporal.Calendar is a representation of a calendar system. It includesinformation about how many days are in each year, how many months are ineach year, how many days are in each month, and how to do arithmetic inthat calendar system.

A Temporal.Duration represents an immutable duration of time which can beused in date/time arithmetic.

A Temporal.Instant is an exact point in time, with a precision innanoseconds. No time zone or calendar information is present. Therefore,Temporal.Instant has no concept of days, months, or even hours.

A Temporal.PlainDate represents a calendar date. "Calendar date" refers to theconcept of a date as expressed in everyday usage, independent of any timezone. For example, it could be used to represent an event on a calendarwhich happens during the whole day no matter which time zone it's happeningin.

A Temporal.PlainDateTime represents a calendar date and wall-clock time, witha precision in nanoseconds, and without any time zone. Of the Temporalclasses carrying human-readable time information, it is the most generaland complete one. Temporal.PlainDate, Temporal.PlainTime, Temporal.PlainYearMonth,and Temporal.PlainMonthDay all carry less information and should be used whencomplete information is not required.

A Temporal.PlainMonthDay represents a particular day on the calendar, butwithout a year. For example, it could be used to represent a yearlyrecurring event, like "Bastille Day is on the 14th of July."

A Temporal.PlainTime represents a wall-clock time, with a precision innanoseconds, and without any time zone. "Wall-clock time" refers to theconcept of a time as expressed in everyday usage — the time that you readoff the clock on the wall. For example, it could be used to represent anevent that happens daily at a certain time, no matter what time zone.

A Temporal.PlainYearMonth represents a particular month on the calendar. Forexample, it could be used to represent a particular instance of a monthlyrecurring event, like "the June 2019 meeting".

A Temporal.TimeZone is a representation of a time zone: either anIANA time zone, includinginformation about the time zone such as the offset between the local timeand UTC at a particular time, and daylight saving time (DST) changes; orsimply a particular UTC offset with no DST.

Options to control the result of until() and since() methods inTemporal types.

Options to control behavior of Duration.compare(), Duration.add(), andDuration.subtract()

A plain object implementing the protocol for a custom time zone.

Options for arithmetic operations like add() and subtract()

Options for assigning fields using with() or entire objects withfrom().

Any of these types can be passed to Temporal methods instead of a Temporal.Calendar.

Options for assigning fields using Duration.prototype.with() or entireobjects with Duration.from(), and for arithmetic withDuration.prototype.add() and Duration.prototype.subtract().

The round method of the Temporal.Duration accepts one requiredparameter. If a string is provided, the resulting Temporal.Durationobject will be rounded to that unit. If an object is provided, thesmallestUnit and/or largestUnit property is required, while otherproperties are optional. A string parameter is treated the same as anobject whose smallestUnit property value is that string.

Options to control behavior of Duration.prototype.total()

When the name of a unit is provided to a Temporal API as a string, it isusually singular, e.g. 'day' or 'hour'. But plural unit names like 'days'or 'hours' are also accepted.

round methods take one required parameter. If a string is provided, theresulting Temporal.Duration object will be rounded to that unit. If anobject is provided, its smallestUnit property is required while otherproperties are optional. A string is treated the same as an object whosesmallestUnit property value is that string.

Any of these types can be passed to Temporal methods instead of a Temporal.TimeZone.

Options for conversions of Temporal.PlainDateTime to Temporal.Instant

Options for outputting precision in toString() on types with seconds

Options to control behaviour of ZonedDateTime.prototype.getTimeZoneTransition()

The Temporal.Now object has several methods which give information aboutthe current date, time, and time zone.