calendars. When a year is completed in a #calendar, a cycle is completed and a new year starts. Not all calendars are based on earth rotating around the sun. Even when they do, they do not have the same starting point nor the same exact length. There is no standard defined by ISO for a year.
A good sense for the concept "year" is problematic. It is very much something that is culturally defined. The English article starts by defining a year as "the orbital period of the earth moving around the sun" to finally acknowledge that a year is more than that. The article is mainly about all the variety that makes a year hard to define.
There is a practical side to all this, The year 2014 could be the year 2014 HS or 2014 CE, 2014 AD, 2014 AH or 2014 AM... It is possible to define the period of this year in any calendar but there should be no doubt what calendar is in use.
The Wikidata item for "2014 AD" defines 2014 as a year that is part of the Gregorian calendar. In this way all years of any calendar can be defined; it is just a matter of qualifying what calendar is used.