year is 365.25 days. In a non-leap year, there are 365 days, in a leap year there are 366 days. A leap year occurs every fourth year during which a leap day is intercalated into the month of February. The name "Leap Day" is applied to the added day.

In astronomy, the Julian year is a unit of time defined as 365.25 days, each of exactly seconds (SI base unit),