A year is the period of time it takes the earth to make a complete revolution around the sun , although the year is not only reduced to the time it takes for the planet earth to rotate, but the phenomenon also extends to the other planets.
A year is made up of 12 months , some like April, June, September and November of 30 days and others like December, January, March, May, July, August and October of 31 days and February, the most “rebellious”, that each four years (leap year) adds one more day to its traditional number of 28.
There are several years according to the reference that you decide to use to determine its duration .
The Sidereal year, for example, is the one that more accurately measures the duration of a year, that is why it is the most used by astronomers and it is the time that elapses between two consecutive steps of the earth through the same point of its orbit, it takes as a reference to the stars and its duration is 365 days, 6 hours, 9 minutes and 9.76 seconds.
On the other hand, we find the tropical year that takes the vernal equinox as a reference and is the time that passes between two successive steps of the Sun through the middle equinox, to be understood, it would be from one spring to the next spring. The duration is 365 days.
And finally, the calendar year, which is the number of complete days considered as a year and which has a high impact on civil and religious matters.
In the West, for example and at the request of the resolution taken by Pope Gregory XIII in 1582, January 1 is the day on which the year changes and for this reason, the object of the traditional celebration that the Western world has celebrated since the last hours of the old year, on December 31st, extending the celebration until a few hours after January 1st itself.
It is almost law on this date, the meeting of the family or otherwise of friends who join together for dinner and wait for the arrival of the new year.