The calendar is one of the most important tools we have for keeping track of time. It helps us know which days things will happen. The first calendars were used by Earthling farmers to decide when to plant and harvest crops. Calendars were very different back then because they had to guess what kind of weather they would have each day. Different places had to use different calendars because different parts of Equestria would have different weather. Each day would even last a different amount of time depending on the season!
Ever since Queen Galaxina first raised the sun, everypony has used the same calendar. There are four days per week, four weeks per moon, four moons per season, and four seasons per year. That means every year has 100 (10000) days in it!
Please pick out a part of the calendar to learn more about.