What is the Hajj observed by Muslims?
What is the observance of the Hajj?
 During Hajj, pilgrims join processions of millions of Muslim people, who simultaneously converge on Mecca for the week of the Hajj, and perform a series of pre-Islamic rituals (reformed by Muhammad): each person wears a single piece of unstitched white clothing (Ihram), walks counter-clockwise seven times around the Kaaba (a cube-shaped building and the direction of prayer for Muslims), kisses the black stone mounted on the corner wall of Kaaba, walks briskly back and forth between the hills of Safa and Marwah seven times, then drinks from the Zamzam Well, goes to the plains of Mount Arafat to stand in vigil, spends a night in the plain of Muzdalifa, and performs symbolic Stoning of the Devil by throwing stones at three pillars. After the sacrifice of cattle (which can be accomplished by using a voucher), the pilgrims then are required to either shave or trim their heads (if male) or trim the ends of their hair (if female). A celebration of the four-day global festival of Eid al-Adha proceeds afterwards.