The Islamic world uses the lunar Hijri calendar to determine the exact days of Islamic holidays and rituals, such as prayer times. Since the Hijri calendar is based on the lunar system, it contains 12 months, which consist of 354 or 355 days. The Hijri calendar was established after the prophet Muhammad and his followers migrated (hijri) from Mecca to Yathrib (now called Medina) and established the first Muslim community in 622 AD. Tthis is the first Islamic New Year. The Gregorian calendar is used for every other aspect of life.
The Feast of the Sacrifice, or Eid al-Adha, is on the 10th day of Dhu al-Hijjah, meaning, "The Month of the Pilgrimage". It is the 12th and last month of the Hijri calendar. Comparatively, the date of Eid al-Adha shifts about 11 days earlier every year on the Gregorian calendar.
The Feast of the Sacrifice, or Eid al-Adha, is one of two major Islamic holidays celebrated worldwide by Muslims, and is considered the holier of the two. Since the lamb was sacrificed in place of Isaac, Muslims commemorate this by sacrificing a sheep, ram, goat, cow, or even a came.
