There are two official holidays in Islam: Eid Al-Fitr and Eid Al-Adha. Eid Al-Fitr is celebrated at the end of Ramadan (a month of fasting), and Muslims usually give zakat (charity) on the occasion. Eid Al-Adha is celebrated on the 10th day of Dhu al-Hijjah and lasts for four days, during which Muslims usually sacrifice an animal and distribute its meat among family, friends, and the poor.
Both holidays occur on dates in the Islamic (Hijri) calendar, which is lunar, and thus their dates in the Gregorian calendar, which is solar, change each year. The Gregorian calendar is based on the orbital period of the Earth's revolution around the Sun, approximately 3651⁄4 days, while the Islamic calendar is based on the synodic period of the Moon's revolution around the Earth, approximately 291⁄2 days. The Islamic calendar alternates months of 29 and 30 days (which begin with the new moon). Twelve of these months constitute an Islamic year, which is 11 days shorter than the Gregorian year.
Ramadan is the month in which Muslims must fast from dawn to sunset. This is meant to feel how the poor people are without food or water. In addition, Muslims fast by denying themselves both food and drink. This, they believe in turn allows for the nourishment of the soul. In addition, there are culture-specific beliefs regarding the watching of television, listening to music, and the perusal of any secular vice that does not in some way enhance spirituality.