Year
From Wikislippy
A year is the time the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
Common Year vs Leap Year
The average length of a year is 365.25 days. In a non-leap year (or common year), there are 365 days, in a leap year there are 366 days. A leap year occurs every 4 years.
