Definition:Calendar/Gregorian/Year

Definition
A Gregorian year, also known as the civil year, is the length of a year as defined using the Gregorian calendar.


 * $1$ Gregorian year $= \begin{cases} 366 \, \text {days} & : 400 \divides y \\

365 \, \text {days} & : 400 \nmid y \text { and } 100 \divides y \\ 366 \, \text {days} & : 100 \nmid y \text { and } 4 \divides y \\ 365 \, \text {days} & : 4 \nmid y \end{cases}$

where:
 * $y$ denotes the number of the year
 * $4 \divides y$ denotes that $y$ is divisible by $4$
 * $4 \nmid y$ denotes that $y$ is not divisible by $4$.

Also known as
A Gregorian year is also known as the civil year.

Some sources also call it a calendar year, which for many societies it actually is.

However, there are some societies which use a different calendars, and so to them a calendar year is a different construct altogether.

Also see

 * Discrepancy between Gregorian Year and Tropical Year