Calendars are timesheets where time is shown in a regular order according to years, months, weeks, and days. Calendars are adjusted according to astronomical observations in the sky. The two most important sky observation vehicles for mankind were the movements of the sun and Moon.
In the past, the Babylonian used the calendar for the first time. The Babylonian calendar, adopted as the first calendar, used the lunar calendar, which was also used by the Islamic realm. The lunar calendar was the calendar based on a period of 29.5 days between the two full moons of the month. According to the lunar calendar, a year is 354 days.
The basis of the Gregorian calendar, which we currently use and used as a universal calendar in the world, was laid in 46 BC with the Julian calendar, created according to the movements of the Sun by Caesar's orders. The beginning of the Julien Calendar began with Caesar's meeting with Cleopatra. In this calendar, which was used until 1582, every 128 per year increased by 1 day due to the failure of the Pope XIII on November 15, 1582. The Gregorian calendar, prepared by Gregory's order, was adopted as the beginning year of the birth of the Prophet Jesus. The Gregorian calendar is 365 days 6 hours a year and the earth around the sun is 365 days 6 hours and the duration is called 1 year.