There are over 40 different calendars used around the world. Many countries and religions have their own calendar to track the days, months, and years. Here are the 3 main types of calendars: 1. Lunar A lunar calendar tracks time using the monthly cycles of the moon’s phases. It measures the time between one new moon to the next. 2. Solar A solar calendar is based on a solar year, which is the time it takes for Earth to rotate around the sun. It measures the time between vernal equinoxes. 3. Lunisolar A lunisolar calendar uses both the moon phases and the time of the solar year to track time.