The calendar is extremely important to society, but there isn’t one specific type of calendar available out there. While the Gregorian calendar is used and accepted throughout the world, many different cultures and religious groups still use other forms of calendars in conjunction with the Gregorian calendar.  The Jewish faith has their own calendar, and it is commonly referred to as the Hebrew calendar or the Jewish calendar.  It is a calendar that shows the phases of the moon as well as the time of the solar year, also called a lunisolar calendar. This is an important one for this faith because it determines the dates of their important Jewish holidays and the appropriate public reading of portions of the Torah. It has many other purposes as well.  The Jewish calendar has evolved over time, changing over the years. The calendar is on a 19 year repeating cycle because there is a discrepancy of about 11 days between one solar year and 12 lunar months. This is important to people who follow the Jewish faith because they need to know when their holidays fall on. The holidays change from year to year and Jewish holidays in 2011 will be very different than they were in 2010 or will be in 2012.  Since there are holidays when Jews are not allowed to work , an accurate calendar that tracks exactly when those holidays will fall is important to the Jewish people.