The feasts and festivals of Islam follow the Islamic calendar, which is a lunar calendar. It began in the year 622, when the Prophet Muhammad moved from Mecca to Medina (hijra, migration). A lunar year is 10 to 11 days shorter than the solar year, so for every 33 solar years there is an extra lunar year. The end of November 2011 was the beginning of the Islamic calendar year 1433. The months of the Islamic hijriyear, which correspond to the months of the lunar year, are known in Arabic as: Muharram, Safar, Rabi’ al-awwal, Rabi’ al-thani, Jumada al-ula, Jumada al-thani, Rajab, Sha’aban, Ramadan, Shawwal, Dhu al-Qi’dah and Dhu al-Hijjah. The names of the months were agreed among Arab tribes in the 460s, or approximately 150 years before Muhammad became the Prophet. The Islamic view is that night precedes day; that is, that each 24-hour period goes from sunset to sunset.
In Islam, the word ’id(or Eid) means an Assembly Day that is repeated. That weekly Assembly Day is Friday, when Muslims around the world gather for Friday prayers (salat al-jum’a) in a mosque or some other place of assembly whenever it is possible to do so shortly after noon. The prayer is preceded by a sermon (khutbah), which is given by the leader of the prayers, an imam.
Every year, two main festivals are celebrated: Eid al-Adha (festival of the sacrifice) and Eid al-Fitr (Feast of Breaking the Fast). In addition to these, there are other days of note in the Islamic calendar.