A calendar year is an approximation of the number of days of the Earth's orbital period as counted in a given calendar.
The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars; see below.
In Israel the academic year begins around October or November, aligned with the second month of the Hebrew Calendar.
Examples include Chinese 年 "year", originally 秂, an ideographic compound of a person carrying a bundle of wheat denoting "harvest".
Slavic besides godŭ "time period; year" uses lěto "summer; year".
A leap year occurs every fourth year, or leap year, during which a leap day is intercalated into the month of February. The Gregorian calendar attempts to cause the northward equinox to fall on or shortly before March 21 and hence it follows the northward equinox year, or tropical year. It is estimated that by the year 4000 CE, the northward equinox will fall back by one day in the Gregorian calendar, not because of this difference, but due to the slowing of the Earth's rotation and the associated lengthening of the day.
The Revised Julian calendar, as used in some Eastern Orthodox Churches, currently does a better job than the Gregorian in synchronizing with the mean tropical year.