The Hajj is one of the five pillars of Islam, and all Muslims are required to undertake it at least once in their lives if they are physically and financially able to do so.
For the pilgrims, it is a profound spiritual experience that wipes away sins, brings them closer to God and highlights Muslim unity.
The pilgrimage draws Muslims from around the world to Mecca, in Saudi Arabia, where they walk in the footsteps of the Prophet Muhammad and retrace the journey of Ibrahim and Ismail.
Muslims do not worship the Kaaba, a cube-shaped structure covered in a black, gold-embroidered cloth, but view it as their most sacred place and a powerful symbol of unity and monotheism.
The Hajj has been held every year since the time of the prophet, even through wars, plagues and other turmoil.
Pilgrims begin by entering a state of spiritual purity known as “ihram.” Women forgo make-up and perfume and cover their hair, while men change into seamless terrycloth robes.
Pilgrims are forbidden from cutting their hair, trimming their nails or engaging in sexual intercourse while in the state of ihram.
Many Muslims visit Medina, where the Prophet Muhammad is buried and where he built the first mosque, before heading to Mecca.
The Hajj begins with Muslims circling the Kaaba in Mecca counter-clockwise seven times while reciting prayers.
Then they walk between two hills in a reenactment of Hagar’s search for water for her son, Ismail, a story that occurs in different forms in Muslim, Christian and Jewish traditions.
The next day, pilgrims head to Mount Arafat, where the Prophet Muhammad delivered his final sermon. Here, they stand in prayer throughout the day asking God for forgiveness of their sins.
Around sunset, pilgrims walk or take buses to an area called Muzdalifa. They pick up pebbles to use the next day in a symbolic stoning of the devil in the valley of Mina, where Muslims believe Ibrahim was tempted to ignore God’s command to sacrifice his son.
The pilgrimage ends with a final circling of the Kaaba and further casting of stones at Mina. Men often shave their heads and women clip a lock of hair, signaling renewal.
The final days of Hajj coincide with Eid al-Adha, or the festival of sacrifice, a joyous occasion celebrated by Muslims around the world to commemorate Ibrahim’s test of faith.