It is a reference system that is used to measure the passage of time. The origins were based on the moon but currently do in the movement of the Earth around the Sun.

Origins

From ancient times man has always been associated with the idea of the time limit to hear such a good time to plant or harvest a crop or to perform religious acts.

The calendars have always been associated with religious customsThe priests were the first to use calendars to mark the celebration of the holidays.

The first people to accurately measure the length of one year through the Egyptian calendar was. This civilization was based on the star Sirius to do so.

A From that time many changes with the passage of civilizations to the point of creating a schedule for each of them.

Types of calendars

Calendars can be divided depending on what the stars are based on:

·  Spots: indicate phases of the moon in its movement around the Earth. These are new moon, full moon, first quarter and fourth shrinking.

·  Solares: identifies the position of the Earth to encircle the sun. Most of the calendars are based on this movement.

·  Lunisolares: is the combination of the movements of the Earth around the Sun and the Moon to encircle the Earth.

·  Siderales: are based on the movements of other stars other than the Sun and Moon.

Calendars depending on the time

There are different types of schedules according to the people that have created. Some of them are:

·  Chinese: is a lunisolar calendar that has its origin in 2637 BC (BC).

·  Hebrew: it is a lunisolar calendar created in the year 359.

·  Gregorian: was established in 1582 by Pope Gregory XIII and is a solar calendar.

·  Islamic: it is a lunar calendar that was created in the year 622. It was created by the departure of Muhammad Mena.

·  Hindu: is native to India and brings together all regional schedules in the country.

In addition to these there are other calendars of lost ancient civilizations which have served as the basis for many others such as the Aztec calendar, the Egyptian, Greek or Julian.

Remarks

At present there is a permanent or perpetual calendar that allows users to easily a given day of any year within a range of several centuries

To know there are several methods such as tables teachers, universal mechanisms used in watches and advanced software. All of them used as a time reference.