We all are familiar with one calendar that is followed in most parts of the world, the calendar with months from January till December. This calendar is the Gregorian calendar, which was introduced several decades ago in 1582 by Pope Gregory XIII and is based on the one complete rotation of Earth around the Sun. Gregorian calendar is the slight modification in the Julian calendar by Pope. Apart from the Gregorian calendar, there are various others for different cultures and religions, as shown in the infographic.
According to the Islamic calendar, Muslims worldwide celebrate their new year; the 1442AH started on August 20, 2020, and will end on August 8, 2021. The dates of the Islamic calendar are based on the moon cycles; hence the number of days every year varies, it has 12 lunar months, and the average number of days each year is around 354 to 355. Saudi Arabia has set the dates on the basis of astronomical calculations of moon cycles; several countries follow Saudi's lead for moon sightings whereas, some spot the moon themselves, which makes a slight difference in the holidays' dates.
Similar to the Islamic calendar, many other regional new year celebrations are done relying on the lunar calendar, which results in changing the dates each year in relation to the Gregorian calendar. This is why Islamic festivals and holidays can occur in any Gregorian month.
