With their palms facing the sky in supplication, and many with tears in their eyes, around two million people from around the world have gathered in an effort to start anew, erase past sins and beg God for forgiveness and guidance in the peak day of the hajj pilgrimage.

From dawn until dusk, the massive crowd of people will be gathered here in Mount Arafat to spend the day in supplication and contemplation. It is here, on this mountain surrounded by desert, where the Prophet Muhammad delivered his final sermon more than 1,400 years ago.

“We hope that Allah will forgive our sins, and we hope to have a new start with our God,” said Khaled Ahmed, a 47-year-old pilgrim from Egypt.

In his sermon, the prophet called on his followers to repay their debts, beware of Satan, perform five daily prayers, fast during the month of Ramadan and give to charity. He also called on those with the means to perform the hajj once in a lifetime. He also reminded worshippers of the rights that women have, and said that no ethnic group or race has superiority over another except in piety and good action.

During the hajj, pilgrims are expected to shed symbols of materialism, though the trip itself can be quite expensive for most. Male pilgrims are required to wear seamless, white terrycloth garments for the entirety of the hajj. Women wear loose clothing, cover their hair and forgo makeup and nail polish to achieve a state of humility and spiritual purity.

The large crowds gathered from more than 160 countries around the world, dressed in nearly identical white garments, are meant to symbolise unity among Muslims, humility and equality before God. The rich and poor among men are to dress the same while performing the rites of hajj.

The hajj is required of all Muslims once in a lifetime. The physically demanding journey tests pilgrims' patience as they withstand long waits and thick crowds on their path to achieving spiritual purification and repentance.

Noura Sulieman, a pilgrim from the Philippines, said she'd been to the hajj many times before and was here again to pray for her family.

“I came here to Arafat to pray for my family, for my daughter, and my son, and all my family, and all the Philippines Muslims, and all Muslims in all countries,” she said. “God willing, Allah will accept our pilgrimage.”

Muslims believe the rites trace the footsteps of the prophets Ibrahim and Ismail — Abraham and Ishmael in the Bible.

The movement of such a large and diverse crowd of people in a short period of time in limited spaces is a logistical challenge for the Saudi government. Authorities have deployed more than 100,000 security forces to secure the hajj and assist pilgrims. Additional doctors, nurses, ambulances and mobile health centres are also deployed in the areas of hajj.

Many begin their pilgrimage by travelling to Medina, the site of both the Prophet Muhammad's first mosque and where he is buried.

The rites of the hajj, however, begin in Mecca, the site of Islam's holiest place of worship. There, pilgrims circulate the cube-shaped Kaaba and kneel in prayer facing it. The Kaaba represents the metaphorical house of God and the oneness of God in Islam. Observant Muslims around the world face toward the Kaaba during the five daily prayers.

Hajj 2017 Show all 16 1 /16 Hajj 2017 Hajj 2017 A Muslim pilgrim partakes in the symbolic stoning of the devil at the Jamarat Bridge in Mina, near Mecca, which marks the final major rite of the hajj Karim Sahib/AFP Hajj 2017 Muslim pilgrims take part in the symbolic stoning of the devil at the Jamarat Bridge in Mina, near Mecca, which marks the final major rite of the hajj Karim Sahib/AFP Hajj 2017 A Muslim pilgrim partakes in the symbolic stoning of the devil at the Jamarat Bridge in Mina Karim Sahib/AFP Hajj 2017 A Muslim pilgrim has his head shaven after throwing pebbles at pillars during the symbolic stoning of the devil Karim Sahib/AFP Hajj 2017 A Muslim pilgrim's head is shaved, after throwing pebbles at pillars during the symbolic stoning of the devil Karim Sahib/AFP Hajj 2017 A Saudi policeman spays Muslim pilgrims with water to cool them off near the Grand Mosque Karim Sahib/AFP Hajj 2017 Muslim pilgrims pray at Mount Arafat, southeast of the Saudi holy city of Mecca Bandar Aldandani/AFP Hajj 2017 Muslim pilgrims at the Grand Mosque Karim Sahib/AFP Hajj 2017 Iranian Muslim pilgrims wait at Jeddah airport in Saudi Arabia prior to the start of the annual Hajj pilgrimage in the holy city of Mecca Karim Sahib/AFP Hajj 2017 Muslim worshippers perform prayers around the Kaaba, Islam's holiest shrine, at the Grand Mosque in Saudi Arabia's holy city of Mecca Karim Sahib/AFP Hajj 2017 An Iranian Muslim pilgrim reads the Koran as she waits at Jeddah airport in Saudi Arabia, prior to the start of the annual Hajj pilgrimage in the holy city of Mecca Karim Sahib/AFP Hajj 2017 Saudi Red Crescent paramedics show the press their emergency equipment Karim Sahib/AFP Hajj 2017 Muslim worshippers perform prayers around the Kaaba, Islam's holiest shrine, at the Grand Mosque in Saudi Arabia's holy city of Mecca Karim Sahib/AFP Hajj 2017 Muslim worshippers perform prayers around the Kaaba, Islam's holiest shrine, at the Grand Mosque in Saudi Arabia's holy city of Mecca Karim Sahib/AFP Hajj 2017 Muslim worshippers walk around the Kaaba, Islam's holiest shrine, at the Grand Mosque in Saudi Arabia's holy city of Mecca Karim Sahib/AFP Hajj 2017 Muslim pilgrims sit around the Kaaba, the cubic building at the Grand Mosque, ahead of the annual Hajj pilgrimage in the Muslim holy city of Mecca Karim Sahib/AFP

After Mecca, pilgrims spend the day in Mount Arafat before heading to an area called Muzdalifa. There, they will pick up pebbles for a symbolic stoning of the devil and a casting away of sins that takes place in the Mina valley for three days.

Male pilgrims will shave their hair and women will cut a lock of hair in a sign of renewal for completing the hajj. Around the world, Muslims will mark the end of hajj with a celebration called Eid al-Adha.