Definition:Time/Unit/Year

Definition
The year is a derived unit of time.

It has various definitions, according to purpose, but the usual "scientific" definition has it as:
 * the orbital period of Earth round the sun
 * $365.242 \,19$ days of $60 \times 60 \times 24$ seconds.

Also see

 * Definition:Julian Year
 * Definition:Sidereal Year
 * Definition:Civil Year

There are others.

Also known as
The year as defined here is also known as a tropical year to distinguish it from the various other types of year.