Abstract is: February 29, also known as leap day or leap year day, is a date added to leap years. A leap day is added in various solar calendars (calendars based on the Earth's revolution around the Sun), including the Gregorian calendar standard in most of the world. Lunisolar calendars (whose months are based on the phases of the Moon) instead add a leap or intercalary month. It is the 60th day of a leap year in the Gregorian calendar, and 306 days remain until the end of the leap year. It is also the last day of February on leap years. It is also the last day of meteorological winter in Northern Hemisphere and the last day of meteorological summer in the Southern Hemisphere on leap years.