The Year is a unit of time not ascribed to those established by the International System. This period of time is comprised of 365 days, this period of time was imposed in ancient times by the Roman Catholic and Apostolic Church relating the events around Jesus Christ reported in the Bible. These events marked a before and after for the society that followed such dogma, so much so that two eras were marked which are known as BC (before Christ) and DC (After Christ). A year is made up of 12 months, each one made up of 30 or 31 days, for a total of 365 days.

The year is a certain period of time, which can be used regardless of the fact that the beginning is not January 1 and the end is December 31, these days are for convenience the first of the first month and the last of the last month, simply, after a period of 365 days is considered to be a year already past. The applications of this term are very varied, very seen, below, a brief summary of the uses that correspond to this term.

The age of people, when someone is born, in the first year for health control reasons, is measured in months, inclusive, even after the year is over, instead of saying that he is 1 year and a half, it is said that he is 18 months, however after this period has passed, the age of people is measured in years, for example, Leonardo is 21 years old, David is 29 years old, Ana is 20 years old. The Year unit is not used to mark eras, that is the work of the decades, however, this word is useful to denote a year in which something characteristic has occurred that will mark the collective memory of society with its details, an example of this, 2012, the Olympic year, since the Olympic Games were held in London, 2001, was a year for terrorism that the world would not forget, since the attack on the twin towers in New York and the Pentagon building in Washington marked the start of a wave of terrorist attacks around the world, as well as wars and deaths.