The word calendar comes from the Latin “calendarum”, the name that the Romans gave to the accounting book and they measure time in lunar cycles; For them, "calenda" was the first day of each month that there was a new moon and it was the day that the bills had to be paid. In ancient Rome, on that day, the accountant arrived with his accounting book (calendarium) to collect. By calendar is understood to be the system and printed record that is used to mark the passage of time organized in years, months and days; where you can usually find information about the phases of the moon, religious and civil festivals. And this creation of man allows him to place himself in time.
Although many civilizations did not develop some type of calendar like the one known today, they were fully aware of the passage of time according to the seasons of nature, or the moon. At present the calendars are divided by years made up of 365 days of 24 hours each; and in the fourth year, one more day would be added by the rotation of the planets around the sun, and these are called solar calendars.
With the passage of time, various types of calendars were created, for example the well-known Gregorian calendar that was established by Pope Gregory XIII in the year 1582, and this counts the leap years every year multiples of four and was created with the objective of modify the error in the Julian calendar. There is also the Israelite calendar that in ancient times the lunar year was made up of twelve months of thirty-nine days and on each other side there is the Muslim calendar, the flora, the ecclesiastical, the republican among many others.
