1224 GMT December 16, 2019
Hajj is one of the world's largest annual religious gatherings.
Each and every able-bodied Muslim, male or female, is required to complete the religious trip at least once in their lifetime if they also have the sufficient financial capacity to do so.
The nearly month-long pilgrimage features various rites, including stoning a column representing the devil, sacrificing sheep in remembrance of Prophet Abraham’s offered sacrifice, and tawaf, which consists of walking and praying around the Kaaba, Islam's holiest site, at the Grand Mosque in Mecca.
In total, some 2.5 million faithful, the majority from abroad, will undertake the pilgrimage this year, according to Saudi media.
"More than 1.8 million visas were delivered online without the need for middlemen. It's a success," said Hajj Ministry official Hatim bin Hassan Qadi.
"It's an indescribable feeling. You have to live it to understand it," said an Algerian in his 50s completing the pilgrimage for the first time.
"It's a golden opportunity and moment," said his female companion.
"The whole world is here... being here in Mecca is the best feeling," said Mohamed Barry, a pilgrim from Britain.
The gathering is also seen as a symbol of Muslim unity, with all participants required to wear a simple and identical outfit during the processions.
The clothing consists of a two-piece white seamless garment for men, and a loose cover-all dress for women.
The scale of the pilgrimage presents vast security and logistical challenges, with tens of thousands of safety officers deployed.
Riyadh faced strong criticism in 2015 when thousands of worshippers were killed in the worst stampede in the gathering's history.
Saudi authorities gave an initial tally of 770 deaths and then stopped updating that figure, even as official counts from individual countries whose nationals had died in the incident rose to more than a total of 2,400 individuals, reaching nearly 5,000 deaths according to some reports.
At least 464 Iranians lost their lives in the incident.
Despite the absence of diplomatic ties between Iran and Saudi Arabia, some 88,550 Iranian pilgrims are due to take part in the Hajj this year.
Tasnim News Agency, Press TV and AFP contributed to this story.