<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The Islamic, Muslim, or Hijri calendar (Arabic: التقويم الهجري ‎ at - taqwīm al - hijrī) is a lunar calendar consisting of 12 months in a year of 354 or 355 days . It is used (often alongside the Gregorian calendar) to date events in many Muslim countries . It is also used by Muslims to determine the proper days of Islamic holidays and rituals, such as the annual period of fasting and the proper time for the pilgrimage to Mecca . </P> <P> The Islamic calendar employs the Hijri era whose epoch was retrospectively established as the Islamic New Year of AD 622 . During that year, Muhammad and his followers migrated from Mecca to Yathrib (now Medina) and established the first Muslim community (ummah), an event commemorated as the Hijra . In the West, dates in this era are usually denoted AH (Latin: Anno Hegirae, "in the year of the Hijra") in parallel with the Christian (AD) and Jewish eras (AM). In Muslim countries, it is also sometimes denoted as H from its Arabic form (سَنة هِجْريّة, abbreviated هـ). In English, years prior to the Hijra are reckoned as BH ("Before the Hijra"). </P>

Islamic calendar how many days in a non leap year