Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, both meaning "to go" generally (compare Vedic Sanskrit éti "goes", atasi "thou goest, wanderest").
Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc.; per annum means "each year", anno Domini means "in the year of the Lord".
The Persian calendar, in use in Afghanistan and Iran, has its year begin at the midnight closest to the instant of the northward equinox as determined by astronomical computation (for the time zone of Tehran), as opposed to using an algorithmic system of leap years.
A fiscal year or financial year is a 12-month period used for calculating annual financial statements in businesses and other organizations.
In the Julian calendar, the average (mean) length of a year is 365.25 days.
In a non-leap year, there are 365 days, in a leap year there are 366 days.
The academic year may be divided into academic terms, such as semesters or quarters.
A year is the orbital period of the Earth moving in its orbit around the Sun.
Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility.
When computations are done involving both years AD and years BC, it is common to use Astronomical year numbering, in which 1 BC is designated 0, 2 BC is designated −1, and so on.
Other eras are also used to enumerate the years in different cultural, religious or scientific contexts.