The very first factor why calendars are important is to arrange your days, seasons, years, and also months. Utilizing a calendar to do this is extremely easy.
The second factor is the same as the first one, but it is a lot more difficult and requires some computations. This is the solar year calendar. The solar year is a human creation. The solar year refers to the Julian calendar as well as is used to figure out the Gregorian calendar. Both calendars are practically the same except for the leap year, which is two times a year in the Gregorian calendar.
Source image: pinterest.com