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, so that Hajj and Ramadan fall sometimes in summer, sometimes in winter). Pilgrims wear special clothes: simple garments which strip away distinctions of class and culture, so that all stand equal before God. (Pilgrims praying at the mosque in Makkah.)

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 did Hagar during her search for water. Then the pilgrims stand together on the wide plain of Arafa and join in prayers for God's forgiveness, in what is often thought of as a preview of the Last Judgment.

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 and the exchange of gifts in Muslim communities everywhere. This, and the Eid al-Fitr, a feast-day commemorating the end of Ramadan, are the main festivals of the Muslim calendar.