The types of calendars used by societies have varied throughout history. According to the education website EDinformatics, lunar calendars are synchronized to the phases of the moon, whereas solar calendars are linked to the perceived movement of the sun causing the changes of the seasons. Lunisolar calendars are linked to both the movement of the moon and the apparent movement of the sun.
According to EDinformatics, experts believe that lunar calendars are the oldest type. The Islamic calendar is an example of a lunar calendar. The Julian calendar, a type of solar calendar, came into existence during the Roman Empire. As with lunar calendars, the Julian calendar always gradually becomes desynchronized with the seasons. For that reason, the Gregorian calendar was adopted by most of the Western world beginning in 1582 and has since become the world's dominant calendar for civic purposes. The Jewish calendar is an example of a lunisolar calendar.
Some ancient calendars seem to have been synchronized to the movement of the planet Venus, including some of the ancient Egyptian calendars. Other calendars, called arbitrary calendars, are not linked at all to solar movement. A fiscal calendar is one type of arbitrary calendar.