Printed calendars, in addition to its main function to display dates and related information, usually in a table format, also often contain additional information relevant for specific groups – for instance, a Christian liturgical calendar will show holy days and liturgical colours, while a calendar for amateur astronomers will highlight phases of the moon, conjunctions and eclipses. Calendars for general public may also contain various interesting facts (e.g., associated with anniversaries of important people or important events). Various facts were also printed on the back sides of the sheets of a tear-off calendar. In modern times, calendars may also have a decorative purpose.