There have been numerous incidents during the Hajj, the Muslim pilgrimage to the city of Mecca, that have caused loss of life. Every follower of Islam is required to visit Mecca during the Hajj at least once in his or her lifetime, if able to do so; according to Islam, the pilgrimage is one of the Five Pillars of Islam. During the month of the Hajj, Mecca must cope with as many as three million pilgrims.Plane travel makes Mecca and the Hajj more accessible to pilgrims from all over the world. As a consequence, the Hajj has become increasingly crowded. City officials are required to control large crowds and provide food, shelter, sanitation, and emergency services for millions. Despite these efforts, incidents have still occurred.