Nearly 1.5 million Muslims from around 150 countries began the annual Hajj pilgrimage to Mecca, Islam's holiest site, in Saudi Arabia on Saturday.
The Hajj is one of the five pillars of Islam, recreating the journey taken by the Prophet Mohammed about 1,400 years ago.
All able-bodied Muslims are required to do Hajj once in their lifetime if they can afford it.
During the pilgrimage, women forgo makeup and perfume while men dress in seamless, white robes. These restrictions are meant to emphasise the equality of all Muslims and prevent wealthier pilgrims from differentiating themselves with more elaborate garments.
Pilgrims begin Hajj by circling Kaaba, one of the the holy shrines in Islam, seven times. After spending the night in the massive valley of Mina, they head to Mount Arafat, some 20 kilometers east of Mecca, for the pinnacle of the pilgrimage.
Around sunset, pilgrims head to an area called Muzdalifah, nine kilometers (5.5 miles) west of Arafat. They spend the night there and pick up pebbles along the way that will be used in a symbolic stoning of the devil back in Mina.
The number of pilgrims is less than last year due to the absence of tens of thousands of Iranians. Tensions between Saudi Arabia and Iran have flared over a stampede last year which killed 2,000 people, including hundreds of Iranians.
Last May, officials from the two countries held talks over arrangements for Iranian citizens in relation to the pilgrimage but failed to reach an agreement.
This year the Saudi Government has taken a number of safety measures in order to prevent another stampede.
In order to free up space in Mina, where the stampede took place, government facilities have been moved out of the area and the roads near the Jamarat Bridge have been expanded.
Officials have also been issuing pilgrims with bracelets that digitally store their personal data, after some foreign officials expressed concern about difficulties in identifying those killed in past stampedes.
No figure for the number of bracelets distributed so far has been released.