The annual pilgrimage to Makkah - the Hajj - is an obligation only for those who are physically and financially able to perform it. Nevertheless, about two million people go to Makkah each year from every corner of the globe, providing a unique opportunity for those of different nations to meet one another. Although Makkah is always filled with visitors, the annual Hajj begins in the twelfth month of the Islamic year (which is lunar, not solar, meaning that Hajj and Ramadan rotate throughout every season). Pilgrims wear special clothes: simple garments which strip away distinctions of class and culture, so that all stand equal before God.
The rites of the Hajj, which are of Abrahamic origin, include circling the Ka'ba seven times, and going seven times between the mountains of Safa and Marwa as Hagar did during her search for water. Then the pilgrims stand together on the wide plain of Arafat and join in prayers for God's forgiveness.
In previous centuries the Hajj was an arduous undertaking. Today, however, Saudi Arabia provides millions of people with water, modern transport, and the most up-to-date health facilities.
The close of the Hajj is marked by a festival, the Eid al-Adha, which is celebrated with prayers, slaughtering an animal to feed the needy, and the exchange of gifts in Muslim communities everywhere. This, and the Eid al-Fitr, a celebration commemorating the completion of the fasting of Ramadan, are the two holidays celebrated by Muslims worldwide.