Linked from

The 26 pages that link to Leap year, each with the reason it gives.

• Gregorian calendarRelated: The Gregorian calendar adds February 29 in years divisible by four, with century-year exceptions.

• Julian calendarBroader topic: The Julian calendar adds February 29 every fourth year.

• Tropical yearRelated: Leap days compensate for the tropical year’s fractional number of days.

• Earth's orbitRelated: The calendar compensates for Earth's orbital year being longer than 365 days.

• IntercalationBroader topic: A leap year applies intercalation at the scale of a whole year.

• CalendarBroader topic: The Gregorian calendar uses an extra day to track the tropical year.

• Pope Gregory XIIIRelated: Gregory’s reform refined leap-year rules to reduce long-term calendar drift.

• Calendar reformRelated: Leap-year rules regulate the mismatch between whole calendar days and the tropical year.

• Birthday ProblemRelated: Including February 29 changes the number of birthday categories in the model.

• SolsticeRelated: Leap days help prevent solstice dates from drifting steadily through the calendar.

• Sidereal yearCompared with: Calendar corrections follow the tropical year, not the sidereal year.

• Solar yearRelated: Leap days compensate for the seasonal year’s fraction beyond 365 days.

• June solsticeRelated: Leap days help prevent the June solstice from drifting through the calendar year.

• JanuaryRelated: Leap years change February’s length, not January’s.

• MonthRelated: The Gregorian calendar adds its leap day to February.

• Solar calendarRelated: Adding a day periodically prevents seasonal dates from drifting through the calendar.

• Christopher ClaviusRelated: The Gregorian reform changed leap-year frequency to reduce calendar drift.

• FebruaryRelated: February receives the added day in years designated as leap years.

• 21st centuryRelated: Leap-year rules determine the century's calendar structure and its final year's status.

• AprilRelated: Leap years alter February, leaving April’s length unchanged.

• JulyRelated: Leap years adjust February, leaving July’s 31-day length unchanged.

• JuneCompared with: June’s length stays fixed when February gains a leap day.

• OctoberRelated: Leap years add a day to February, but October always has 31 days.

• Year 2000 problemRelated: Incorrect century handling could affect whether systems treated 2000 as a leap year.

• New YearRelated: Leap-year rules regulate year length without changing the January 1 boundary.

• Year (calendar)Broader topic: Its added day makes some calendar years 366 days long.